Power supply systems and feedback through a transformer

ABSTRACT

A power converter circuit includes a transformer. The transformer includes a primary winding and a secondary winding. A primary circuit is coupled to the primary winding. A secondary circuit is coupled to the secondary winding. The primary circuit and the secondary circuit are referenced to different ground voltage potentials that may vary with respect to each other. During operation, the primary circuit controls input of energy to the primary winding of the transformer. The secondary circuit receives the energy through the secondary winding and uses it to produce an output voltage to power a load. The secondary circuit receives and/or generates state information at one of multiple different levels. The secondary circuit controls a flow of current through the secondary winding to convey the state information as feedback to the primary circuit. The primary circuit analyzes a voltage at a node of the primary winding to receive the feedback.

RELATED APPLICATIONS

This application is related to and claims the benefit of earlier filedU.S. Provisional Patent Application Ser. No. 62/299,146 entitled “ POWERSUPPLY SYSTEMS AND FEEDBACK THROUGH A TRANSFORMER,” (Attorney Docket No.IMU16-01(2016P50262)p, filed on Feb. 24, 2016, the entire teachings ofwhich are incorporated herein by this reference.

BACKGROUND

A typical flyback converter includes a primary side circuit, atransformer, and a secondary side circuit. The primary side circuit isconnected to a power source and includes at least one switching elementthat controls the amount of energy transferred to the secondary side viathe transformer. The transformer serves as an electrically isolatedchannel to transfer energy from the primary side circuit to thesecondary side circuit. The secondary side circuit is coupled to a loadto be powered.

In a traditional flyback converter, at least one diode coupled in acurrent path of a secondary side winding of the transformer is includedto block current (e.g., from flowing from the transformer to thesecondary side circuit when the primary side transistor is turned on orfrom flowing from an output capacitor on the secondary side to thesecondary side winding and back to the primary side). One disadvantageof using a diode in the secondary side circuit is that, when the primaryside switching element is turned off and energy is transferred from thetransformer to the secondary side circuit (and the load), energy is lostdue to a voltage drop (RDS-ON) over the diode. To improve efficiency,some flyback converters may be configured such that the traditionaldiode is replaced by, or put in parallel with, an active element (e.g.,one or more transistors), which may be referred to as a secondary sideswitching element. Such a secondary side switching element may beoperated to switch in synchronization with switching behavior of theprimary side switching element, which may increase efficiency comparedto the using a diode as described above. Operation of the secondary sideswitching element in synchronization with switching behavior of theprimary side switching element may be referred to as synchronousrectification. Generally, there are two ways to implement synchronousrectification: the first way is referred to as “control-driven”synchronous rectification, and the second way is known as “self-driven”synchronous rectification.

In a control-driven scheme, the secondary side switching element isdriven by gate-drive signals that are derived from the gate-drive signalof the primary side switching element. In other words, thecontrol-driven scheme generally requires information to pass, via one ormore additional electrically isolated signal paths or communicationlinks other than the transformer, from a primary side circuit of theflyback to a secondary side circuit of the flyback. Using theinformation received via the additional electrically isolated signalpaths, sent from the primary side, a secondary side controller candetermine the state of the gate-drive signals controlling the primaryside switching element. Based on the state of the gate-drive signalscontrolling the primary side switching element, the secondary sidecircuit can determine when to cause the secondary side switching elementto turn-on or turn-off in synchronization with the primary sideswitching element. Since a control-driven synchronous rectificationcontrol scheme uses an additional, communication link, control-drivensynchronous rectification may increase size, cost, and/or complexity ofthe flyback power converter.

Self-driven synchronous rectification may be more attractive for someflyback applications since self-driven control is simpler and requiresfewer components than the control driven scheme. In a self-drivenscheme, a secondary side controller may forgo the information about thestate of the gate-drive signals controlling the primary side switchingelement, received from the primary side circuit via the additional,communication link, and instead may simply monitor energy (e.g., acurrent and/or voltage of energy) being transmitted to the secondaryside circuit via the transformer. Based on the monitored energy, thesecondary side controller can control the secondary side switchingelement to switch in-synchronization with the operations of the primaryside switching element. Although the reliance on a self-drivensynchronous rectification control scheme may decrease size, cost, and/orcomplexity as compared to a control-driven scheme, self-drivensynchronous rectification may sacrifice accuracy and quality of aflyback converter by producing a lower quality and less efficient poweroutput.

BRIEF DESCRIPTION (MULTI-BIT FEEDBACK THROUGH TRANSFORMER)

Embodiments herein include novel ways of communicating data (stateinformation) through a transformer circuit.

More specifically, embodiments herein include a transformer including aprimary winding and a secondary winding. A primary circuit is coupled tothe primary winding. A secondary circuit is coupled to the secondarywinding. During operation, the primary circuit controls input of energyto the primary winding of the transformer. In one non-limiting exampleembodiment, the secondary circuit receives the energy and uses it toproduce an output voltage to power a load.

To input energy to the transformer, the primary circuit controls aprimary switch (in the primary circuit) to control a flow of currentthrough the primary winding of the transformer. The flow of currentthrough the primary winding stores a quantum of energy in thetransformer.

Subsequent to storage, the secondary circuit receives the energy storedin the transformer through the secondary winding of the transformer. Forexample, in one embodiment, the secondary circuit operates a secondaryswitch in the secondary circuit to control a flow of current through thesecondary winding of the transformer to receive the energy and producean output voltage to power load.

In furtherance of maintaining the magnitude of the output voltage withina desired output voltage range, the secondary circuit compares amagnitude of the output voltage to a reference voltage. The differencebetween the magnitude of the output voltage and the reference voltagerepresents an error signal. The secondary circuit produces feedbackbased on the error signal to facilitate control of inputting subsequentenergy to the primary winding.

In one embodiment, the secondary circuit communicates the feedbackthrough the secondary winding to the primary winding. In this exampleembodiment, the feedback indicates a particular state selected amongstmultiple possible states (i.e., any suitable type of information such ascommands, messages, error information, etc.) associated with derivingthe output voltage from the energy received through the secondarywinding. Thus, different states of feedback can be conveyed through thesecondary winding to the primary winding.

In accordance with further embodiments, to convey the feedback throughthe second winding to the primary winding, the secondary circuitcontrols a secondary switch (in the secondary circuit) to control a flowof current through the secondary winding to communicate the feedbackthrough the transformer to the primary winding. In one embodiment, thesecondary circuit controls conveyance of the feedback through thetransformer at a time when the primary circuit is in an inactive state(i.e., when the primary circuit no longer inputs energy into thetransformer through the primary winding).

In one embodiment, the secondary circuit controls a duration ofconveying current through the secondary winding to indicate a state ofthe feedback, which may be one of multiple different states.

To receive the feedback, the primary circuit monitors a magnitude of avoltage at the node of the primary winding. The input of the feedback(current) through the secondary winding causes a perturbation inmagnitude of the voltage at the node of the primary winding. In oneembodiment, the perturbation of the magnitude of the voltage at the nodeof the primary winding is a peak transition or valley transition thatoccurs within a monitored window of time. A range in which the peak orvalley transition falls indicates a respective state of the feedbackinformation conveyed from the secondary circuit through the secondarywinding to the primary winding.

As previously discussed, and as further described herein, the feedbackrepresents a signal encoded at any of one or more different levels. Thatis, each of the different selectable levels represents a differentpossible state.

In further embodiments, in response to receiving the feedback, andselected state information from the multiple possible states, theprimary circuit uses the feedback to control subsequent input of aquantum of energy to the primary winding.

In this manner, feedback from a secondary circuit can be encoded toconvey any of multiple different states of state information through asecondary winding to a primary winding of a transformer. The receivedstate information can be used for any suitable purpose such as i)controlling delivery of subsequent energy through the primary windingthrough the transformer to the secondary winding, ii) conveying generalstatus information or messages from the secondary circuit to the primarycircuit, iii) controlling commands from the secondary circuit to theprimary circuit, etc.

Embodiments herein provide advantages over conventional techniques. Forexample, it is widely known that data can be transferred through acommunication path outside of the transformer, such as via use of anextra opto-coupler circuit or a second high frequency transformer toconvey communications. Embodiments herein would require no additionalcommunication components, which increases power density and reduce powerconsumption, especially in the case of stand power requirements.

These and other more specific embodiments are disclosed in more detailbelow.

The embodiments as described herein are advantageous over conventionaltechniques. For example, the embodiments as discussed herein areapplicable to transformer circuitry and corresponding power convertercircuits. The concepts disclosed herein, however, are applicable to anyother suitable topologies as well general applications of conveyingstate information form one circuit to another.

Note that embodiments herein can include a controller configuration ofcomputer processor hardware to carry out and/or support any or all ofthe method operations disclosed herein. In other words, one or morecomputerized devices or processors (computer processor hardware) can beprogrammed and/or configured to operate as explained herein to carry outdifferent embodiments of the invention.

Yet other embodiments herein include software programs to perform thesteps and operations summarized above and disclosed in detail below. Onesuch embodiment comprises a computer program product that hasnon-transitory computer-storage media (e.g., memory, disk, flash, . . .) including computer program logic encoded thereon that, when performedin a computerized device having a processor and corresponding memory,programs the processor to perform any of the operations disclosedherein. Such arrangements are typically provided as software, codeand/or other data (e.g., data structures) arranged or encoded on acomputer readable storage medium or non-transitory computer readablemedia such as an optical medium (e.g., CD-ROM), floppy or hard disk orother a medium such as firmware or microcode in one or more ROM or RAMor PROM chips, an Application Specific Integrated Circuit (ASIC), etc.The software or firmware or other such configurations can be installedonto a controller to cause the controller to perform the techniquesexplained herein.

Accordingly, one particular embodiment of the present disclosure isdirected to a computer program product that includes a computer readablemedium having instructions stored thereon for supporting operations suchas controlling phases in a power supply. For example, in one embodiment,the instructions, when carried out by a computer processor hardware,causes the computer processor hardware to: input energy to a primarywinding of a transformer; receive the energy through a secondary windingof the transformer; derive an output voltage from the energy receivedthrough the secondary winding; and communicate feedback through thesecondary winding to the primary winding, the communicated feedbackrepresenting state information, the state information indicating aparticular state selected amongst multiple possible states.

The ordering of the steps has been added for clarity sake. These stepscan be performed in any suitable order.

It is to be understood that the system, method, device, apparatus, etc.,as discussed herein can be embodied strictly as hardware, as a hybrid ofsoftware and hardware, or as software alone such as within a processor,or within an operating system or a within a software application.

Note that although each of the different features, techniques,configurations, etc., herein may be discussed in different places ofthis disclosure, it is intended, where appropriate, that each of theconcepts can optionally be executed independently of each other or incombination with each other. Accordingly, the one or more presentinventions as described herein can be embodied and viewed in manydifferent ways.

Also, note that this preliminary discussion of embodiments hereinpurposefully does not specify every embodiment and/or incrementallynovel aspect of the present disclosure or claimed invention(s). Instead,this brief description only presents general embodiments andcorresponding points of novelty over conventional techniques. Foradditional details and/or possible perspectives (permutations) of theinvention(s), the reader is directed to the Detailed Description sectionand corresponding figures of the present disclosure as further discussedbelow.

BRIEF DESCRIPTION (MULTI-MODAL OPERATION)

Embodiments herein include novel ways of utilizing feedback receivedthrough a transformer circuit to produce an output voltage.

More specifically, embodiments herein include a transformer including aprimary winding and a secondary winding. A primary circuit is coupled tothe primary winding.

A secondary circuit is coupled to the secondary winding.

During operation in each cycle of multiple cycles, the primary circuitcontrols input of energy to the primary winding of the transformer. Inone non-limiting example embodiment, the secondary circuit receives theenergy and uses it to produce an output voltage to power a load. Toinput energy to the transformer, the primary circuit controls a primaryswitch (in the primary circuit) to control a flow of current through theprimary winding of the transformer. The flow of current through theprimary winding stores a quantum of energy in the transformer.Subsequent to storage, the secondary circuit receives the energy storedin the transformer through the secondary winding of the transformer. Forexample, in one embodiment, the secondary circuit operates a secondaryswitch in the secondary circuit to control a flow of current through thesecondary winding of the transformer to receive the energy and producean output voltage to power load.

In furtherance of maintaining the magnitude of the output voltage withina desired output voltage range, during each cycle, the secondary circuitcompares a magnitude of the output voltage to a reference voltage. Thedifference between the magnitude of the output voltage and the referencevoltage represents an error signal. When the error signal indicates thatthe magnitude of the output voltage has reached a threshold value, thesecondary circuit responds by producing feedback through the secondarywinding to the primary winding of the need for more energy to producethe output voltage.

Over multiple cycles, the timing of receiving the feedback will varydepending on power consumption by the load. For example, when the loadconsumes a relatively large amount of current, the time in which thesecondary circuit transmits feedback for more energy is relativelyshort. Conversely, when the load consumes a relatively small amount ofcurrent, the time in which the secondary circuit transmits feedback formore energy is relatively long.

The secondary circuit monitors a timing of receiving the feedback in arespective cycle to control subsequent energizing of the primary windingand respective operation of the power converter circuit in one of twomodes.

For example, the power converter circuit operates in a first mode (suchas fixed frequency, variable pulse width of energizing the primarywinding) when the load consumes relatively little energy. Conversely,the power converter circuit operates in a second mode (such as variablefrequency, fixed pulse width of energizing the primary winding) when theload consumes relatively high energy.

Switching the power converter circuit between operational modes isuseful for multiple reasons. For example, in the first mode, a lowestfrequency of operating the power converter circuit can be maintainedwell above the range of human hearing. Additionally, in the first mode,adjusting the pulse width of energizing the primary winding to berelatively short during low load conditions reduces a magnitude ofripple voltage on the output voltage. The shortened pulse widthssupported by the first mode also prevents loss of excess energy in thetransformer because the inputted quantum of energy is used to power theload as opposed to be lost in the transformer.

These and other more specific embodiments are disclosed in more detailbelow.

The embodiments as described herein are advantageous over conventionaltechniques. For example, the embodiments as discussed herein areapplicable to transformer circuitry and corresponding power convertercircuits. The concepts disclosed herein, however, are applicable to anyother suitable topologies as well general applications of conveyingstate information form one circuit to another.

Note that embodiments herein can include a controller configuration ofcomputer processor hardware to carry out and/or support any or all ofthe method operations disclosed herein. In other words, one or morecomputerized devices or processors (computer processor hardware) can beprogrammed and/or configured to operate as explained herein to carry outdifferent embodiments of the invention.

Yet other embodiments herein include software programs to perform thesteps and operations summarized above and disclosed in detail below. Onesuch embodiment comprises a computer program product that hasnon-transitory computer-storage media (e.g., memory, disk, flash, . . .) including computer program logic encoded thereon that, when performedin a computerized device having a processor and corresponding memory,programs the processor to perform any of the operations disclosedherein. Such arrangements are typically provided as software, codeand/or other data (e.g., data structures) arranged or encoded on acomputer readable storage medium or non-transitory computer readablemedia such as an optical medium (e.g., CD-ROM), floppy or hard disk orother a medium such as firmware or microcode in one or more ROM or RAMor PROM chips, an Application Specific Integrated Circuit (ASIC), etc.The software or firmware or other such configurations can be installedonto a controller to cause the controller to perform the techniquesexplained herein.

Accordingly, one particular embodiment of the present disclosure isdirected to a computer program product that includes a computer readablemedium having instructions stored thereon for supporting operations suchas controlling phases in a power supply. For example, in one embodiment,the instructions, when carried out by a computer processor hardware,causes the computer processor hardware to: operate a power convertercircuit to input energy to a primary winding of a transformer andsubsequently receive the energy through a secondary winding of thetransformer over each of multiple cycles, the power converter circuitproducing an output voltage using the energy received through thesecondary winding; over a range of different magnitudes of powerdelivered by the output voltage to a dynamic load, switch modaloperation of the power converter circuit between a first mode and asecond mode based on a timing of feedback (indicating a request for moreenergy) conveyed from the secondary winding to the primary winding overeach of the multiple cycles.

Another particular embodiment of the present disclosure is directed to acomputer program product that includes a computer readable medium havinginstructions stored thereon for supporting operations such ascontrolling phases in a power supply. For example, in one embodiment,the instructions, when carried out by a computer processor hardware,causes the computer processor hardware to: control operation of a powerconverter circuit to input energy to a primary winding of a transformerand receive the energy through a secondary winding of the transformer;produce an output voltage using the energy received through thesecondary winding; and vary a timing of conveying feedback (with respectto receiving energy through the secondary winding) to the primarycircuit over multiple cycles to maintain a magnitude of the outputvoltage within a desired range.

The ordering of the steps has been added for clarity sake. These stepscan be performed in any suitable order.

It is to be understood that the system, method, device, apparatus, etc.,as discussed herein can be embodied strictly as hardware, as a hybrid ofsoftware and hardware, or as software alone such as within a processor,or within an operating system or a within a software application.

Note that although each of the different features, techniques,configurations, etc., herein may be discussed in different places ofthis disclosure, it is intended, where appropriate, that each of theconcepts can optionally be executed independently of each other or incombination with each other. Accordingly, the one or more presentinventions as described herein can be embodied and viewed in manydifferent ways.

Also, note that this preliminary discussion of embodiments hereinpurposefully does not specify every embodiment and/or incrementallynovel aspect of the present disclosure or claimed invention(s). Instead,this brief description only presents general embodiments andcorresponding points of novelty over conventional techniques. Foradditional details and/or possible perspectives (permutations) of theinvention(s), the reader is directed to the Detailed Description sectionand corresponding figures of the present disclosure as further discussedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments herein, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, with emphasis instead being placed uponillustrating the embodiments, principles, concepts, etc.

FIG. 1 is an example general diagram of a power converter circuitaccording to embodiments herein.

FIG. 2 is an example more detailed diagram illustrating a powerconverter circuit including a transformer and corresponding circuitryaccording to embodiments herein.

FIG. 3 is an example diagram illustrating different possible voltagevariations of an output voltage according to embodiments herein.

FIG. 4 is an example timing diagram illustrating input of feedbackthrough a secondary winding and receipt of the feedback over a node of aprimary winding according to embodiments herein.

FIG. 5 is an example diagram illustrating control of current through asecondary winding to convey corresponding feedback to a primary windingaccording to embodiments herein.

FIG. 6 is an example timing diagram illustrating monitoring of a voltageon a node of the primary winding to receive feedback according toembodiments herein.

FIG. 7 is an example diagram illustrating computer processor hardwareand related software to execute methods according to embodiments herein.

FIGS. 8-10 are example diagrams illustrating methods according toembodiments herein.

FIG. 11 is an example block diagram illustrating adjustment of a pulseduration of energizing a primary winding based on feedback to control aswitching frequency of energizing the primary winding to a desiredsetpoint frequency according to embodiments herein.

FIG. 12 is an example diagram illustrating switching frequency versuspower consumption and efficiency versus power consumption according toembodiments herein.

FIGS. 13 and 14 are example timing diagrams illustrating a firstoperational mode of adjusting pulse durations of energizing the primarywinding based on feedback according to embodiments herein.

FIGS. 15-19 are example timing diagrams illustrating a secondoperational mode of varying a frequency of energizing the primarywinding based on feedback according to embodiments herein.

FIGS. 20-22 are example timing diagrams illustrating use of multi-levelfeedback to control a magnitude of an output voltage according toembodiments herein.

FIGS. 23-26 are example diagrams illustrating methods according toembodiments herein.

FIG. 27 is an example timing diagram illustrating control of providingfeedback through the secondary winding to the primary winding accordingto embodiments herein.

FIG. 28 is an example timing diagram illustrating overcurrent controlaccording to embodiments herein.

DETAILED DESCRIPTION

Now, more specifically, FIG. 1 is an example diagram of a powerconverter circuit according to embodiments herein.

As shown, the power converter circuit 100 includes primary (side)circuit 121, transformer circuitry 130, secondary (side) circuit 122.Transformer circuitry 130 includes primary winding 131 and secondarywinding 132.

In one embodiment, transformer circuitry 130 is a so-called air gaptransformer in which the transformer circuitry 130 stores energyreceived through the primary winding 131 for subsequent conveyancethrough the secondary winding 132.

In accordance with further embodiments, during operation, powerconverter circuit 120 receives input voltage 120 from input voltagesource 119. As its name suggests, the power converter circuit 120converts the input voltage 120 into output voltage 190 to power dynamicload 118.

More specifically, to convert the input voltage 120 into the outputvoltage 190, the primary circuitry 121 of power converter circuit 100inputs energy (from input voltage 120 and corresponding flow of current)through the primary winding 131 of transformer circuitry 130. Thesecondary circuit 122 receives the energy through the secondary winding132 of the transformer circuitry 130.

As further shown, the secondary circuit 124 receives and/or generatesstate information 139 and conveys it as feedback 142 in a reversedirection to the primary circuit 122. The state information 139 can beany suitable type of information.

In one embodiment, the secondary circuit 122 selects the stateinformation 139 in which to convey back to the primary circuit 121 asfeedback 142. For example, via different feedback communications, thesecondary circuit 122 is operable to select a first state (of stateinformation) to notify the primary circuit 121 of a selected firststate; the secondary circuit 122 is operable to select a second state(of state information) to notify the primary circuit 121 of the selectedsecond state; the secondary circuit 122 is operable to select a thirdstate (of state information) to notify the primary circuit 121 of theselected third state; and so on.

In one embodiment, as further described herein in greater detail, thecommunicated feedback 142 and corresponding state information 139includes the selected state information 139. In this manner, thesecondary circuit 122 is able to communicate different types of data(states) from the secondary circuit 122 to the primary circuit 122without having to implement extra communication circuitry such as anopto-coupler or extra transformer between the primary circuit 121 andthe secondary circuit 122. Accordingly, embodiments herein reduce thenumber of components needed to implement power converter circuit 100,reduces a corresponding circuit footprint of the power converter circuit100, reduces costs of fabricating power converter circuit 100, etc.

The secondary circuit 122 uses the energy received though the secondarywinding 132 to produce the output voltage 190. By further way ofnon-limiting example, the state information 139 can include informationindicating a current or previous state associated with the deriving theoutput voltage 190 from the energy received through the secondarywinding 122.

More specifically, in one embodiment, the secondary circuit 122 monitorsthe magnitude of output voltage 190 and controls it to be within adesired voltage range. In such an instance, the primary circuit 121 usesthe received feedback 142 to control subsequent input of energy to thetransformer circuitry 130 through the primary winding 131. As discussedbelow, by way of non-limiting example embodiment, the feedback 142 canindicate a quantum of energy to input to the primary winding 131 on asubsequent control cycle to maintain the output voltage 190 within adesired range.

Note that each of the primary circuit 121 and secondary circuit 122 caninclude any suitable analog circuitry, digital circuitry, or acombination of both. Additionally, the each of the primary circuit 121and secondary circuit 122 can be or include a computer, processor,micro-controller, digital signal processor, etc., configured to carryout and/or support any or all of the method operations disclosed herein.

Note further that embodiments herein can further include one or moresoftware programs, executable code stored on a computer readable mediato perform the steps and operations summarized above and disclosed indetail below. For example, one such embodiment comprises a computerprogram product that has a computer-storage medium (e.g., anon-transitory computer readable medium or media) including computerprogram logic (e.g., software, firmware, instructions, . . . ) encodedthereon that, when performed in the respective circuit having aprocessor and corresponding storage, programs the circuit to digitallyperform the operations as disclosed herein. Such arrangements can beimplemented as software, code, and/or other data (e.g., data structures)arranged or encoded on a computer readable medium such as an opticalmedium (e.g., CD-ROM), floppy or hard disk or other a medium such asfirmware or microcode in one or more ROM or RAM or PROM chips, anApplication Specific Integrated Circuit (ASIC), etc. The software orfirmware or other such configurations can be stored in or may beaccessible to the respective circuits to perform the techniquesexplained herein.

Accordingly, in addition to hardware and/or firmware, embodiments of thepresent disclosure are directed to a computer program product thatincludes a non-transitory computer readable medium (e.g., memory,storage repository, optical disk, integrated circuit, etc.) to executeany of the operations as described herein.

FIG. 2 is an example diagram illustrating more specific details of apower converter circuit including a transformer and correspondingcircuitry according to embodiments herein.

As previously discussed, power converter circuit 100 includestransformer circuitry 130 including primary winding 131 and secondarywinding 132. Power converter circuit 100 further includes primarycircuit 121 and secondary circuit 122.

As further shown in this example embodiment, the primary circuit 121includes primary control circuit 221 to control operation of switchcircuitry 231. The switch circuitry 231 can be or include any suitabletype of switch devices. In one embodiment, the switch circuitry 231 is afield effect transistor. However, note that the switch circuitry 231 canbe any suitable device or combination of devices that control a flow ofcurrent through the primary winding 131.

Similarly, the switch circuitry 232 controlled by secondary controlcircuit 222 can be or include any suitable type of one or more switchdevices to control a flow of current through the secondary winding. Inone embodiment, the switch circuitry 232 is a field effect transistor.However, as mentioned, the switch circuitry 232 can include any suitabledevice to control current flow.

Activation of the switch circuitry 231 (that is, turning switchcircuitry 231 to an ON state) causes current to flow through the primarywinding 131 as received from voltage source 119. Accordingly, thevoltage source 119 provides the energy to input into the primary winding131.

Note that the input voltage 120 can be received from any suitableresource. In one embodiment, the input voltage 120 is a DC or AC voltagederived from full-wave rectification of an AC signal (such as an ACpower signal from a wall receptacle). Accordingly, the input voltage 120can be susceptible to having anywhere from minimal to substantial ripplevoltage.

Note further in this example embodiment that the primary circuit 121 isconnected to a first ground reference voltage, GND1. The secondarycircuit 122 is connected to a second ground reference voltage, GND2.Transformer circuitry provides voltage isolation between the primarycircuit 121 and the secondary circuit 122.

There may be substantial differences associated with ground referencevoltage GND1 and ground reference voltage GND2 over time. In otherwords, one ground reference voltage may be floating with respect to theother ground reference voltage. The differences (and potentially varyingdifferences) between the ground reference voltages can render itchallenging to support communications between the secondary circuit 122in the primary circuit 120, and vice versa.

As previously discussed, use of one or more opto-coupler devices is oneoption for supporting communications between circuits referenced todifferent ground potentials. However, use of such devices is undesirablebecause it increases the cost of the power converter circuit 100 as wellas requires more circuit board space to fabricate the power convertercircuit 100.

As further discussed below, embodiments herein include one or more novelembodiments of communicating state information in a reverse directionfrom the secondary winding through the transformer circuitry 132 theprimary winding 131.

Subsequent to inputting a desired amount of energy into the primarywinding 131 of the transformer circuitry 130 via activation of theswitch circuitry 231, the primary control circuit 221 discontinuesactivation of the switch circuitry 231. That is, the power controlcircuitry 221 turns the switch circuitry 231 to an OFF state. The energystored in the transformer circuitry 130 is now available to thesecondary circuit 122 through secondary winding 132.

Subsequent to controlling the switch circuitry 231 to the OFF state, thesecondary control circuit 222 controls switch circuitry 232 from an OFFstate to an ON state to retrieve the energy stored in the transformercircuitry 130. This causes a flow of current through the secondarywinding 132 to charge the output capacitor 210 and/or deliver current tothe dynamic load 118. Accordingly, via activation of the switchcircuitry 232, the secondary control circuit 222 initiates a transfer ofthe energy stored in the transformer circuitry 130 to power load and/orcharge the output capacitor 210.

In certain instances, it is desirable to maintain a magnitude of theoutput voltage 190 within a predetermined voltage range. In furtheranceof maintaining the magnitude of the output voltage 190 within a desiredoutput voltage range, the monitor circuit 242 of secondary circuit 122can be configured to compare a magnitude of the output voltage 190 to areference voltage 252. The difference between the magnitude of theoutput voltage 190 and the reference voltage 252 represents an errorsignal inputted to the secondary control circuitry 222.

Based on the received error signal, the secondary control circuit 222produces feedback 142 (such as a control signal or error signal) tofacilitate control of inputting subsequent energy to the primary winding131. This can include mapping the detected error to appropriate stateinformation.

In one embodiment, the feedback 142 and corresponding state information139 conveyed to the primary circuit 121 includes or is an error signalgenerated by the monitor circuit 242. Accordingly, the primary circuit121 is apprised of how to control input of subsequent energy into theprimary winding 131 to maintain the output voltage 190 within range.

As previously discussed, the input of energy into the primary winding131 has a direct effect on the magnitude of producing the output voltage190. The secondary control circuitry 222 can be configured to producethe state information 139 indicating how to adjust input of futureenergy into the primary winding 131 to maintain the output voltage 190within a desired voltage range.

As its name suggests, the dynamic load 118 is susceptible to consuming avarying amount of current over time. As will be discussed later in thespecification more detail, the feedback 142 including state information139 can information indicating one of multiple levels of energy toinputted into the primary winding 131 to maintain the output voltage 190within a desired range. During a condition in which the load 118consumes more and more current over time, in which a magnitude of theoutput voltage may be dropping, the feedback 142 conveyed to the primarycircuit 121 can indicate to the primary circuit 121 to input a greateramount of energy into the primary winding 131 during a next input cycleto account for the increase in current consumption.

Conversely, during a condition in which the load 118 consumes lesscurrent overtime, in which a magnitude output voltage may be increasing,the feedback 142 conveyed to the primary circuit 121 can indicate to theprimary circuit 121 to input a lesser amount of energy into the primarywinding 131 on one or more next input cycles to account for a decreasein current consumption.

FIG. 3 is an example diagram illustrating voltage variations of anoutput voltage according to embodiments herein.

As shown in timing diagram 300, and as previously discussed, themagnitude of the output voltage 190 as monitored by the monitor circuit242 of the secondary control circuitry 222 can vary depending on currentconsumption by the dynamic load 118. For example, when the dynamic load118 increases consumption of current supplied through output voltage190, the magnitude of the output voltage 190 dips below the desiredvoltage magnitude level 310 by different amounts. As shown, a greaterrate of increased current consumption occurring within a respectivewindow of time causes the magnitude of the output voltage 190 to fallfurther (as a greater negative voltage transient) below the desiredvoltage magnitude 310.

Conversely, when the dynamic load 118 decreases consumption of currentprovided by the output voltage 190, the magnitude of the output voltage190 jumps above the desired voltage magnitude level 310 because lesscurrent is consumed. As further shown, the greater a rate of decreasedcurrent consumption occurring within the window of time causes themagnitude of the output voltage 190 to increase further (as a greaterpositive voltage transient) above the desired voltage magnitude level310.

In one embodiment, the secondary control circuitry 222 maps thedifferent detected voltage levels to different state informationdepending on the amount of overshoot or undershoot detected at timeTsample.

For example, at time Tsample, if the monitor circuit 242 detects thatthe magnitude of the output voltage 190 falls within the voltage rangeR1, the secondary control circuitry 222 sets the state information 139to level H3 (such as a first multi-bit value, first symbol, etc.);

if the monitor circuit 242 detects that the magnitude of the outputvoltage 190 falls within the voltage range R2, the secondary controlcircuitry 222 sets the state information 139 to level H2 (such as asecond multi-bit value, second symbol, etc.);

if the monitor circuit 242 detects that the magnitude of the outputvoltage 190 falls within the voltage range R3, the secondary controlcircuitry 222 sets the state information 139 to level H1 (such as athird multi-bit value, third symbol, etc.);

if the monitor circuit 242 detects that the magnitude of the outputvoltage 190 falls within the voltage range R4, the secondary controlcircuitry 222 sets the state information 139 to level NOMINAL (such as afourth multi-bit value, fourth symbol, etc.);

if the monitor circuit 242 detects that the magnitude of the outputvoltage 190 falls within the voltage range R5, the secondary controlcircuitry 222 sets the state information 139 to level L1 (such as afifth multi-bit value, fifth symbol, etc.);

if the monitor circuit 242 detects that the magnitude of the outputvoltage 190 falls within the voltage range R6, the secondary controlcircuitry 222 sets the state information 139 to level L2 (such as asixth multi-bit value, sixth symbol, etc.);

if the monitor circuit 242 detects that the magnitude of the outputvoltage 190 falls within the voltage range R7, the secondary controlcircuitry 222 sets the state information 139 to level L3 (such as aseventh multi-bit value, seventh symbol, etc.); and so on.

Note that splitting of the possible transient conditions into 7 possibleranges (and corresponding states) is shown by way of non-limitingexample only. The number of possible selectable states can varydepending on the embodiment.

FIG. 4 is an example timing diagram illustrating input of feedbackthrough a secondary winding and receipt of the feedback on a primarywinding according to embodiments herein.

As shown, the primary control circuitry 221 activates the switchcircuitry 231 to an ON state (while switch circuitry 232 is set to anOFF state by secondary control circuitry 232) between time T1 and T2 ofcycle #1. This causes the current IDSL to flow through the primarywinding 131, storing a corresponding quantum of energy in thetransformer circuitry 130. Between time T2 and time T3, the primarycontrol circuitry 221 controls the switch circuitry 231 to an OFF state.Between time T2 and T3, the secondary control circuitry 222 controls theswitch circuitry 232 to an ON state. This causes the current IDS2 toflow through the secondary winding 131, conveying the energy in thetransformer circuitry 132 to the output capacitor 210 and/or dynamicload 118.

In one embodiment, the secondary control circuitry 222 turns the switchcircuitry 232 to a respective OFF state at time T3 in response todetecting that IDS2 is substantially 0 amps at time T3, corresponding toa condition in which the secondary winding 132 no longer deliverspositive current to the output capacitor 210 and/or load 118.

As previously discussed, the monitor circuit 242 monitors the magnitudeof the output voltage 190. In one embodiment, the monitor circuit 242monitors the magnitude of the output voltage 190 (at any suitable timesuch as between time T3 and T4) to determine whether or not themagnitude of the output voltage 190 is within range (regulation). In amanner as previously discussed in FIG. 3, when monitoring the magnitudeof the output voltage 190, the secondary control circuitry 222 producesthe appropriate state information 139 to any of multiple possible states(such as state H3, H2, H1, NOMINAL, L1, L2, or L3).

Further in this example embodiment, the secondary control circuitry 222initiates conveyance of the state information 139 as correspondingfeedback 142 to the primary control circuitry 221 between time T4 andtime T5 as shown in FIG. 5.

FIG. 5 is an example diagram illustrating control of current through asecondary winding to convey corresponding feedback to a primary windingaccording to embodiments herein.

As shown, at or around time T4, the secondary control circuitry 222initiates activation of the secondary switch circuitry 232 to an ONstate to transmit the state information 139 as feedback 142 through thetransformer circuitry 130. Activation of the switch circuitry 232 causesdepletion of at least a portion of energy stored in the output capacitor210. Recall that the energy on output capacitor 210 was retrieved fromthe transformer 130 between time T2 and time T3. Thus, a portion ofenergy previously inputted through the primary winding is used totransmit feedback 142 through the transformer circuitry 130 to theprimary circuit 121.

As further discussed below, the amount of depletion of charge on theoutput capacitor 210 (to transmit the feedback 142) varies dependingupon the state information 139 selected by the secondary control circuit222 to convey to the primary control circuitry 221.

For example, to convey state information 139 equal to state L3 overtransformer circuitry 130 to the primary control circuitry 221, thesecondary control circuitry 222 activates the switch circuitry 232 for atime duration D1, resulting in a first magnitude of negative rampcurrent through the secondary winding 132 as shown. As previouslydiscussed, the output voltage 190 stored on output capacitor 210provides the current to produce the negative ramp current. In such aninstance, to convey state L3, at the corresponding time TL3 associatedwith state information L3, the secondary switch circuit 222 switches theswitch circuitry 232 to an OFF state (corresponding to time T5 in thetiming diagram of FIG. 4).

To convey state information 139 equal to state L2 over transformercircuitry 130 to the primary control circuitry 221, the secondarycontrol circuitry 222 activates the switch circuitry 232 for a timeduration D2, resulting in a second magnitude of negative ramp currentthrough the secondary winding 132 as shown. In such an instance, at thecorresponding time TL2 associated with state information L2, thesecondary switch circuit 222 switches the switch circuitry 232 to an OFFstate (corresponding to time T5 in the timing diagram of FIG. 4).

To convey state information 139 equal to state L1 over transformercircuitry 130 to the primary control circuitry 221, the secondarycontrol circuitry 222 activates the switch circuitry 232 for a timeduration D3, resulting in a third magnitude of negative ramp currentthrough the secondary winding 132 as shown. In such an instance, at thecorresponding time TL3 associated with state information L3, thesecondary switch circuit 222 switches the switch circuitry 232 to an OFFstate (corresponding to time T5 in the timing diagram of FIG. 4).

To convey state information 139 equal to state NOMINAL over transformercircuitry 130 to the primary control circuitry 221, the secondarycontrol circuitry 222 activates the switch circuitry 232 for a timeduration D4, resulting in a fourth magnitude of negative ramp currentthrough the secondary winding 132 as shown. In such an instance, at thecorresponding time TN associated with state information NOMINAL, thesecondary switch circuit 222 switches the switch circuitry 232 to an OFFstate (corresponding to time T5 in the timing diagram of FIG. 4).

To convey state information 139 equal to state H1 over transformercircuitry 130 to the primary control circuitry 221, the secondarycontrol circuitry 222 activates the switch circuitry 232 for a timeduration D5, resulting in a fifth magnitude of negative ramp currentthrough the secondary winding 132 as shown. In such an instance, at thecorresponding time TH1 associated with state information H1, thesecondary switch circuit 222 switches the switch circuitry 232 to an OFFstate (corresponding to time T5 in the timing diagram of FIG. 4).

To convey state information 139 equal to state H2 over transformercircuitry 130 to the primary control circuitry 221, the secondarycontrol circuitry 222 activates the switch circuitry 232 for a timeduration D6, resulting in a sixth magnitude of negative ramp currentthrough the secondary winding 132 as shown. In such an instance, at thecorresponding time TH2 associated with state information H2, thesecondary switch circuit 222 switches the switch circuitry 232 to an OFFstate (corresponding to time T5 in the timing diagram of FIG. 4).

To convey state information 139 equal to state H3 over transformercircuitry 130 to the primary control circuitry 221, the secondarycontrol circuitry 222 activates the switch circuitry 232 for a timeduration D7, resulting in a seventh magnitude of negative ramp currentthrough the secondary winding 132 as shown. In such an instance, at thecorresponding time TH3 associated with state information H3, thesecondary switch circuit 222 switches the switch circuitry 232 to an OFFstate (corresponding to time T5 in the timing diagram of FIG. 4).

In this manner, the secondary control circuit 222 can be configured toselect one of multiple durations to convey different state informationthrough the transformer circuitry 130 to the primary control circuit221.

Note that activation of secondary switch circuitry 232 consumes energystored in the output capacitor 210, reducing the magnitude of the outputvoltage 190, which is beneficial during overshoot voltage conditions onthe output voltage 190. A successively higher amount of energy isconsumed to transmit states H1, H2, and H3 as feedback 142, increasing aresponse time of maintaining the magnitude of the output voltage 190within a desired range. That is, greater consumption of energy on theoutput capacitor 210 to transmit feedback 142 causes a greater drop inthe magnitude of the output voltage 190.

Accordingly, as discussed above, the secondary control circuitry 222 canbe configured to vary a time of activating the switch circuitry 232 toan ON state between time T4 and T5 by different amounts to conveydifferent selected state information (such as any suitable type ofinformation such as commands, messages, error information, etc.) throughthe secondary winding 132 and primary winding 131 of the transformercircuitry 130 to the primary control circuitry 221.

Note again that the state information 139 need not be related togeneration of the output voltage 190 and maintaining it within a desiredrange. State information conveyed through the transformer circuitry 130can be any type of data.

FIG. 6 is an example timing diagram illustrating monitoring of a voltageon the primary winding to receive state information according toembodiments herein.

To receive the feedback 142, which is encoded to include correspondingstate information 139, the monitor circuit 241 of the primary circuit121 monitors a magnitude of a voltage at a respective node 294 of theprimary winding 131. The input of the feedback 142 to the secondarywinding 132 causes a perturbation in the magnitude of the voltage isVDS1 at the node 294 of the primary winding 131 at around time Tv.Monitor circuit 241 monitors the voltage VDS1 in window of time 685 fora voltage transition (peak or valley).

In one embodiment, the perturbation of the magnitude of the voltage atthe node of the primary winding is a peak transition or valleytransition of the VDS1 voltage at the node 294 occurring within amonitored window of time 685 (around time T5).

For example, if the detected valley voltage in the monitored window oftime 685 falls in between voltage range defined by threshold values V0and V1, then the received state information 139 in feedback 142 is L3;

if the detected valley voltage of VDS1 in the monitored window of time685 falls in between voltage V1 and V2, then the received stateinformation 139 in feedback 142 is L2;

if the detected valley voltage of VDS1 in the monitored window of time685 falls in between voltage V2 and V3, then the received stateinformation 139 in feedback 142 is L3;

if the detected valley voltage of VDS1 in the monitored window of time685 falls in between voltage V3 and V4, then the received stateinformation 139 in feedback 142 is NOMINAL;

if the detected valley voltage of VDS1 in the monitored window of time685 falls in between voltage V4 and V5, then the received stateinformation 139 in feedback 142 is H1;

if the detected valley voltage of VDS1 in the monitored window of time685 falls in between voltage V5 and V6, then the received stateinformation 139 in feedback 142 is H2; and

if the detected valley voltage of VDS1 in the monitored window of time685 falls in between voltage V6 and V7, then the received stateinformation 139 in feedback 142 is H3.

As previously discussed, the feedback 142 is encoded to represent any ofone or more different levels (such as H3, H2, H1, NOMINAL, L1, L2, orL3). That is, each of the different levels represents a differentpossible state.

In response to receiving the feedback 142, and selected stateinformation 139, the primary circuit 121 uses the feedback to controlsubsequent input of a quantum of energy to the primary winding 131.Accordingly, the state information 139 can indicate error dataassociated with the generated output voltage 190 with respect to areference voltage 252.

In one embodiment, the power converter circuit 221 uses the receivedstate information 139 detected around time T5 to determine how muchenergy to input into the primary winding 131 on a subsequent cycle suchas between time T6 and T7. For example, the secondary control circuitry221 selectively adjusts a timing (i.e., pulse duration) of activatingswitch circuitry 231 depending on the received state information 139.

More specifically, if the received state information 139 indicates astate of NOMINAL, the power converter circuit 221 controls the switchcircuitry 231 to an ON state between time T6 and time T7 to be the sameas the duration of ON time between time T1 and time T2 to deliver a samequantum of energy to the primary winding 131 in cycle #2 as was inputtedduring cycle #1.

If the received state information 139 indicates a state of L1, the powerconverter circuit 221 controls a pulse duration of the switch circuitry231 to an ON state between time T6 and time T7 to be greater (by a firstamount) than the duration of ON time between time T1 and time T2 todeliver a greater quantum of energy to the primary winding 131 in cycle#2 as was inputted during cycle #1.

If the received state information 139 indicates a state of L2, the powerconverter circuit 221 controls the switch circuitry 231 to an ON statebetween time T6 and time T7 to be greater (by a second amount) than theduration of ON time between time T1 and time T2 to deliver a yet greaterquantum of energy to the primary winding 131 in cycle #2 as was inputtedduring cycle #1.

If the received state information 139 indicates a state of L3, the powerconverter circuit 221 controls the switch circuitry 231 to an ON statebetween time T6 and time T7 to be greater than (by a third amount) theduration of ON time between time T1 and time T2 to deliver a stillgreater quantum of energy to the primary winding 131 in cycle #2 as wasinputted during cycle #1.

If the received state information 139 indicates a state of H1, the powerconverter circuit 221 controls the switch circuitry 231 to an ON statebetween time T6 and time T7 to be less than (by a first amount) theduration of ON time between time T1 and time T2 to deliver a smallerquantum of energy to the primary winding 131 in cycle #2 as was inputtedduring cycle #1.

If the received state information 139 indicates a state of H2, the powerconverter circuit 221 controls the switch circuitry 231 to an ON statebetween time T6 and time T7 to be less than (by a second amount) theduration of ON time between time T1 and time T2 to deliver a yet smallerquantum of energy to the primary winding 131 in cycle #2 as was inputtedduring cycle #1.

If the received state information 139 indicates a state of H3, the powerconverter circuit 221 controls the switch circuitry 231 to an ON statebetween time T6 and time T7 to be greater (by a third amount) than theduration of ON time between time T1 and time T2 to deliver a stilllesser quantum of energy to the primary winding 131 in cycle #2 as wasinputted during cycle #1.

Thus, feedback 142 from the secondary circuit 222 can be used toregulate the magnitude of the output voltage 190, cycle after cycle,based on upon a degree to which the secondary control circuitry 222indicates how to adjust subsequent input of energy into the primarywinding 131 as specified by the subsequent cycles of receiving stateinformation 139. In other words, the secondary circuit 122 transmitsfirst state information during cycle #1 (such as NOMINAL), second stateinformation (such as state L1) during cycle #2, third state information(such as state L2) during cycle #3, fourth state information (such asstate L1) during cycle #4, fifth state information (such as stateNOMINAL) during cycle #5, and so on.

In one embodiment, the adjustments to the delivery of a respectivequantum of energy in each next successive cycle can depend on factorssuch as a size of output capacitor 210, desired magnitude of the outputvoltage 190, current consumption by dynamic load 118, magnitude of theinput voltage 121, etc. Note that the power converter circuit 221optionally maps the received state information 139 in feedback 142 to acorresponding positive, zero, or negative time adjustment value toadjust delivery of energy on a next cycle.

Thus, the feedback 142 received over multiple cycles can indicate toincrease or decrease a rate of inputting energy into the primary winding131. More specifically, to accommodate different levels of droop on themagnitude of the output voltage 190 below a desired setting, the primarycontrol circuit 221 increases energy inputted to primary winding 131 ona next one or more cycles. To accommodate different levels of overshooton the output voltage 190, the primary control circuit 221 decreasesenergy inputted to primary winding 131 on a next one or more cycles.

FIG. 7 is an example block diagram of a computer device for implementingany of the operations as discussed herein according to embodimentsherein.

As shown, computer system 800 such as in primary circuit 121 and/orsecondary circuit 122 of the present example includes an interconnect811 that couples computer readable storage media 812 such as anon-transitory type of media (i.e., any type of hardware storage medium)in which digital information can be stored and retrieved, a processor813 (e.g., computer processor hardware such as one or more processordevices), I/O interface 814, and a communications interface 817.

I/O interface 814 provides connectivity to any suitable circuitry suchas primary winding 131, secondary winding 132, etc.

Computer readable storage medium 812 can be any hardware storageresource or device such as memory, optical storage, hard drive, floppydisk, etc. In one embodiment, the computer readable storage medium 812stores instructions and/or data used by the management application 140-1to perform any of the operations performed by primary circuit 121 orsecondary circuit 122.

Further in this example embodiment, communications interface 817 enablesthe computer system 800 and processor 813 to communicate over a resourcesuch as network 193 to retrieve information from remote sources andcommunicate with other computers.

As shown, computer readable storage media 812 is encoded with managementapplication 140-1 (e.g., software, firmware, etc.) executed by processor813. Management application 140-1 can be configured to includeinstructions to implement any of the operations as discussed herein.

During operation of one embodiment, processor 813 accesses computerreadable storage media 812 via the use of interconnect 811 in order tolaunch, run, execute, interpret or otherwise perform the instructions inmanagement application 140-1 stored on computer readable storage medium812.

Execution of the management application 140-1 produces processingfunctionality such as management process 140-2 in processor 813. Inother words, the management process 140-2 associated with processor 813represents one or more aspects of executing management application 140-1within or upon the processor 813 in the computer system 150.

In accordance with different embodiments, note that computer system maybe a micro-controller device configured to control a power supply andperform any of the operations as described herein.

Functionality supported by the different resources will now be discussedvia flowcharts in FIGS. 8-10. Note that the steps in the flowchartsbelow can be executed in any suitable order.

FIG. 8 is a flowchart 800 illustrating an example method according toembodiments. Note that there will be some overlap with respect toconcepts as discussed above.

In processing operation 810, the primary circuit 121 inputs energy (viaflow of current sourced from input voltage 120) to the primary winding131 of transformer circuitry 130.

In processing operation 820, the secondary circuit 122 receives theenergy through the secondary winding 132 of the transformer circuitry130.

In processing operation 830, the secondary circuit 122 produces outputvoltage 190 from the energy received through the secondary winding 132.

In processing operation 840, the secondary circuit 122 communicatesfeedback 142 through the secondary winding (such as via controlling aflow of current sourced from the output voltage 120 or other source) tothe primary winding 131. The communicated feedback 142 indicates aparticular state selected by the secondary circuit 122 amongst multiplepossible states. Accordingly, the secondary circuit 122 is able toconvey multi-level information or multi-bit data back to the primarycircuit 121 through the transformer circuitry 130.

FIG. 9 is a flowchart 900-1 illustrating an example method according toembodiments herein. Note that there will be some overlap with respect toconcepts as discussed above.

In processing operation 910, the primary circuit 121 inputs energy toprimary winding 131 of transformer circuitry 130. In one embodiment, insub-operation 920, the primary circuit 121 controls a flow of currentthrough the primary winding 131 of the transformer circuitry 130 tostore the energy in the transformer circuitry 130.

In processing operation 930, the primary circuit 121 receives the energythrough the secondary winding 132 of the transformer circuitry 130. Insub-operation 940, the primary circuit 121 controls a flow of currentthrough the secondary winding 132 of the transformer circuitry 132 toreceive the energy.

In processing operation 950, the primary circuit 121 uses the receivedenergy to produce an output voltage 190 to power dynamic load 118.

In processing operation 960, the monitor circuit 242 of primary circuit121 compares a magnitude of the output voltage 190 to a referencevoltage 252.

In processing operation 970, the primary circuit 121 produce feedback142 to control delivery of subsequent energy inputted to the primarywinding 131 to maintain the magnitude of the output voltage 190 within adesired voltage range.

FIG. 10 is a flowchart 900-2 illustrating an example method according toembodiments. Note that there will be some overlap with respect toconcepts as discussed above.

In processing operation 1010, the secondary circuit 122 communicates thefeedback 142 through the secondary winding 132 to the primary winding131. The communicated feedback 142 indicates a particular state selectedamongst multiple possible states (such as commands, messages, errorinformation, etc.) associated with deriving the output voltage 190 fromthe energy received through the secondary winding 132. In sub-processingoperation 1020, the primary circuit 121 controls a flow of currentthrough the secondary winding 132 to communicate the feedback 142 fromthe secondary winding 132 to the primary winding 131.

In processing operation 1030, the primary circuit 121 receives thefeedback 142 as a signal at the primary winding 131. In one embodiment,the signal is a perturbation of voltage at a node 294 of the primarywinding 131.

In processing operation 1040, the primary circuit 121 analyzes amagnitude of the voltage at the node 294 of the primary winding 131 toobtain the state information associated with the feedback 142.

In processing operation 1050, the primary circuit 121 utilizes the stateinformation 139 received in the feedback 142 to control subsequent inputof a quantum of energy to the primary winding 131 to control the outputvoltage 190 within the desired range.

Note again that techniques herein are well suited for use in powerconverter circuit applications such as those that implement atransformer. However, it should be noted that embodiments herein are notlimited to use in such applications and that the techniques discussedherein are well suited for other applications as well.

For example, the feedback technique can also operate with analogueinformation where the output voltage error can be translated directlyinto corresponding NCRT (Negative Current Request Times) (linear ornon-linear relation) or through a look-up table (LUT). The valleyvoltage detection on the primary side detection (through some form ofvoltage divider, e.g. resistive or capacitive) can then translate thisinto variable on-time, again this can be linear, non-linear or throughLUT. In the analogue form of VFTT (Voltage Feedback ThroughTransformer), it can operate the full control of the transformercircuitry 130 without the VOT (Variable On Time) concept while stillmaintaining the fast reaction times and reduction in component counts.Note further that analogue or digital form of the voltage feedbackthrough the transformer is not limited to use of a flyback; it may beused for other topologies such as 2-transistor flyback and may becombined with variable on-time control or constant on-time controlrespectively

Multi-Modal Operation—Variable Frequency vs. Fixed Frequency

Embodiments herein further include switching modal operation of thepower converter circuit 100 between a first mode (fixed frequency,variable pulse width) and a second mode (variable frequency, fixed pulsewidth) over a range of different magnitudes of power delivered by theoutput voltage 190 to a dynamic load 118.

As further discussed below, the power converter circuit 100 switchesbetween the operational modes based on feedback 142 conveyed from thesecondary winding 132 to the primary winding 131 over each of themultiple cycles. The secondary control circuit 222 initiatestransmission of the feedback 142 when additional energy is needed tomaintain the output voltage 190 within a desired range. In oneembodiment, receipt of feedback 142 at the primary control circuit 221indicates i) degradation of the magnitude of the output voltage 190below a threshold value, and/or ii) a request for input of energy intothe primary winding. As further described herein, if desired, thefeedback 142 can include state information 139 (multi-level data)indicating a magnitude in which to modify subsequent input of energy tothe primary winding 131.

More specifically, FIG. 11 is an example block diagram illustratingfixed frequency mode including adjustment of a pulse duration ofenergizing a primary winding based on feedback to control a switchingfrequency of energizing the primary winding to a desired setpointfrequency according to embodiments herein.

In this example embodiment including analog and/or digital circuitry, tocontrol the switching frequency about a desired setpoint, the primarycontrol circuit 221 compares the actual switching frequency 1108 ofinputting energy into the primary winding 131 to a desired setpointswitching frequency 1120. In one embodiment, the desired (setpoint)switching frequency 1120 corresponds to a minimal frequency ofenergizing the primary winding 131.

To maintain the actual switching frequency 1110 at or above the desiredsetpoint switching frequency 1120, the primary control circuit 221modifies the pulse width of energizing the primary winding 131 toincrease or decrease the frequency as is needed to keep the frequency ator above the desired switching frequency 1120.

FIG. 12 is an example diagram illustrating switching frequency versuspower consumption and efficiency versus power consumption associatedwith multi-mode operation of the power converter circuit according toembodiments herein.

As previously discussed, the primary control circuit 221 of primarycircuit 121 modifies the rate and/or duration of energizing the primarywinding 131 over time to maintain the output voltage 190 within adesired range.

Graph 1205 indicates an example switching frequency profile ofenergizing the primary winding 131 over a range of consumption by thedynamic load 118. In general, operation of the power converter circuit100 switches between the first mode (fixed frequency) and the secondmode (variable frequency) depending on a timing of receiving thefeedback 142 with respect to a reference time value over each ofmultiple cycles.

For this example profile, during conditions of operating between 0 and60% of maximum power consumption, the primary circuit 121 makes one ormore adjustments to the pulse duration of energizing the primary winding131 to control a frequency of energizing the primary winding 131 to bearound 70 KHz. Above 60% consumption levels, the power converter circuit100 operates in a variable frequency mode (such as between 70 and 100KHz) to maintain the output voltage 190 within a desired range.

Graph 1215 illustrates the efficiency of producing the output voltage190 over the full range of different power consumption levels. As shown,the efficiency of operating the power converter circuit 100 is greaterthan 95%, regardless of whether the power converter circuit 100 isoperated in a variable frequency mode or a fixed frequency mode.

As mentioned, the graphs 1205 and 1215 correspond a chosen profile inwhich the controller attempts to prevent the switching frequency to fallbelow a threshold value of 70 KHz for loads below 60%; the controlleroperates in a variable frequency mode above 60% of full load. Inaccordance with further embodiments, note that the profile of switchingfrequency versus power consumption can be modified to suit any desiredapplication. For example, if desired, the controller can be configuredto modify the pulse duration of energizing the primary winding 131 athigher power consumption levels, while operating in a variable frequencymode at lower power consumption levels.

First Operational Mode of Multi-Modal Operation—Fixed Frequency,Variable Pulse Width

FIGS. 13 and 14 are example timing diagrams illustrating a firstoperational mode of adjusting pulse durations of energizing the primarywinding based on feedback to control a switching frequency according toembodiments herein.

As shown in the timing diagram of FIG. 13, the secondary control circuit222 controls a timing of conveying feedback 142 through the secondarywinding 131 to the primary winding 132 to maintain a magnitude of theoutput voltage 190 within a desired range. For example, when more energyis needed by the secondary control circuit 222 to produce the outputvoltage 190, the secondary control circuit 222 generates and conveysfeedback 142 through the secondary winding 131 to the primary winding132. The feedback 142 in the following figures indicates a request formore energy to be input to the primary winding 131. (Note that use ofmulti-level feedback 142 will be discussed in subsequent FIGS. 20-22.)

In accordance with further embodiments, the secondary control circuitry222 monitors the output voltage 190. In response to detecting that themagnitude of the output voltage 190 has degraded with respect to asetpoint reference voltage such as above a threshold difference value,the secondary control circuitry 222 communicates the correspondingfeedback 142 through the secondary winding 132 to the primary winding131. Thus, rather than sending feedback 142 at pre-specified timeintervals, the secondary control circuitry 222 delays and/or controlsthe timing of conveying the feedback 142 through the secondary winding132 to the primary winding 131 until a time of detecting that additionalenergy is needed to produce the output voltage 190.

In one embodiment, the primary control circuit 221 includes timer 1210to maintain the actual switching frequency 1108 to the desired switchingfrequency 1120. As shown in FIG. 12, the primary control circuit 221starts the timer 1210 at time X11. Between time X11 and X12 (100nanoseconds), the primary control circuit 221 activates switch circuitry231 to energize the primary winding 131. In response to detecting theinput of the energy into the primary winding 131, the secondary controlcircuitry 222 synchronously receives the energy via activation of theswitch circuitry 232 between times X12 and X13 to control currentthrough the secondary winding 132.

In this example, the secondary control circuit 222 inputs feedback 142into the secondary winding 132 at around time X21. In response todetecting and receiving the feedback 142 at the primary winding 131 in amanner as previously discussed above, the primary control circuitry 221stops the timer 1210. In this example embodiment, the timer valueindicates an elapsed duration of 20 μs. This value is substantiallylarger than the 10 μs setpoint time value 1230 (which corresponds to 100kHz).

In furtherance of maintaining the actual switching frequency 1108 toaround the value of 100 KHz, the primary control circuitry 221 comparesthe time (20) captured by the timer 1210 to the setpoint (10). In oneembodiment, the secondary control circuitry 221 determines a differencebetween the time of receiving the feedback 142 and the referencesetpoint of 10 μs. In this example, the secondary control circuit 221subtracts 10 μs from the 20 μs in timer 1210. Accordingly, the actualswitching frequency 1110 is well below the desired switching frequencyof 100 kHz.

To reduce the switching frequency on a subsequent demand cycle, thesecondary control circuit 221 modifies the pulse width of energizing theprimary winding 131 on a subsequent cycle. For example, in the cyclenumber X, the primary control circuit 221 sets the pulse width ofactivating the switch circuitry 231 to be 100 ns between times X11 andX12. To increase the actual frequency 1108, the primary controlcircuitry 221 reduces the pulse width of activating the primary winding131 from 100 ns in cycle X to 75 ns in the subsequent cycle X+1.Assuming that power consumption by the load 118 is constant, decreasingthe pulse width between times X21 and X22 to 75 nS reduces the time ofreceiving a subsequent request for additional energy as shown in FIG. 14on a subsequent cycle X+1 because more energy will be needed sooner on anext cycle.

Referring now to FIG. 14, at time X21, the primary circuit controlcircuitry 221 resets and then starts the timer 1210 again. The primarycontrol circuitry 221 stops the timer 1210 upon receipt of feedback 142from the secondary control circuit 222 just prior to time X31. Thiscorresponds to a duration of 15 μs, which is still substantially longerthan the desired setpoint of 10 μs. Accordingly, on subsequent cycleX+2, in furtherance of maintaining the actual frequency 1108 to benearer to the desired frequency 1120 (power converter circuit 100 KHz),the primary control circuitry 221 reduces the pulse duration ofenergizing the primary winding 131 on cycle X+2 to 50 nS between timeX31 and X32. Thus, because the time of 15 uS is greater than thesetpoint time value 1230, the primary control circuit 221 reduces thecurrent pulse width from 75 nS to 50 nS.

In a similar manner as previously discussed, during cycle X+2, theprimary control circuitry 221 resets and then starts timer 1210 at timeX31. The primary switch circuitry 221 stops the timer 1210 upon receiptof feedback 142 just prior to time X41. This corresponds to a durationof 10 μs, which is still substantially equal to the desired setpoint of10 μs. In response to detecting that the time of 10 μs as captured bythe timer 1210 is substantially equal to the setpoint time value 1230,the primary control circuit 221 sets a magnitude of the pulse durationof energizing the primary winding 131 on the next cycle (X+3) betweentime X41 and X42 (50 nS) to be substantially the same as a pulseduration of energizing the primary winding on the cycle (X+2) betweentime X31 and X32 (50 nS).

Accordingly, embodiments herein include starting a timer 1210 to trackpassage of time; and using the timer 1210 to determine a time ofreceiving feedback at the primary winding 131. In the above exampleembodiment, the primary control circuit 221 decreases the pulse durationof energizing the primary winding 131 on a second cycle with respect toa magnitude of a pulse duration of energizing the primary winding 131 onthe first cycle to maintain frequency operation of energizing theprimary winding over multiple cycles to be above or equal to a frequencythreshold value.

Note that the magnitude of adjustment applied to the pulse duration ofenergizing the primary winding 131 can vary depending upon the timing ofreceiving the feedback 142 in a given cycle. For example, the primarycontrol circuitry 221 may receive the feedback 142 at a duration of 11μs (instead of 20 μs) after starting the timer 1210. In such aninstance, the difference is only one microsecond. Because the differencein this instance is very small, the primary control circuitry 221 mayreduce a pulse width on this next cycle by 1% (instead of 33%) withrespect to the pulse duration in the previous cycle.

Conversely, the primary control circuitry 221 may receive the feedback142 at a duration of 30 μs after starting the timer 1210. In such aninstance, the difference is 20 microseconds. Because the difference inthis instance is very large, the primary control circuitry 221 mayreduce the pulse width on the next cycle by 50% or more with respect tothe pulse duration in the previous cycle.

Thus, embodiments herein can include generating a difference valueindicating a time difference between the time of receiving the feedbackin a cycle and the setpoint time value 1230. The primary control circuit221 uses the difference value to proportionally adjust a magnitude of apulse duration of energizing the primary winding 131 on a next cycle.

Note further that the primary control circuit 221 can be configured tomake very small changes to the pulse width cycle over cycle. In such aninstance, it may take longer for the primary control circuit 221 tocontrol the switching frequency to a desired setpoint in response tolarge load changes in the load.

Accordingly, VOT (Variable On Time) control of the primary winding 131can be used to control the switching frequency of operation of the powerconverter circuit 100 to be within a desired range.

Second Operational Mode of Multi-Modal Operation—Variable Frequency

FIGS. 15-18 are example timing diagrams illustrating a secondoperational mode of varying a frequency of energizing the primarywinding based on feedback according to embodiments herein.

Recall that the second operational mode includes varying a frequency ofinputting energy into the primary winding 131 based on feedback 142 fromthe secondary control circuit 222.

As shown in the timing diagram of FIG. 15, and as previously discussed,the primary control circuit 221 includes timer 1210. The primary controlcircuit 221 starts the timer 1210 at time Y11. Between time Y11 and Y12(i.e., for a duration of 50 nanoseconds), the primary control circuit221 activates switch circuitry 231 to energize the primary winding 131.In response to detecting the input of energy into the primary winding131, the secondary control circuit 222 synchronously receives the energyinputted to the primary winding 131 via activation of the switchcircuitry 232 between times Y12 and Y13. The secondary control circuitry222 delivers the energy to load 118 and/or output capacitor 210.

Further in this example embodiment, the primary control circuit 221receives feedback 142 around time Y21. The feedback 142 is a request foradditional energy.

In response to receiving the feedback 142 indicating that the secondarycontrol circuitry 222 needs more energy to maintain the output voltage190, the primary control circuit 221 stops the timer 1210 and comparesthe corresponding time value of 7.5 μs to the setpoint time value 1230(10 μs). In this example embodiment, in response to detecting that thetime 7.5 μs is less than the setpoint time value 1230, the primarycontrol circuit 221 increases the pulse duration of energizing theprimary winding 131 on the cycle Y+1 with respect to a magnitude of thepulse duration of energizing the primary winding on the cycle Y. Morespecifically, in response to receiving the feedback 142 just before timeY21, the primary control circuitry 221 energizes the primary winding 131between time Y21 and time Y22 (75 nS) to accommodate, for example, anincreased consumption of power by load 118.

As shown in the timing diagram of FIG. 16, the primary control circuit221 starts the timer 1210 at time Y21. Between time Y21 and Y22 (i.e.,for a duration of 75 nanoseconds), the primary control circuit 221activates switch circuitry 231 to energize the primary winding 131. Inresponse to detecting the input of energy into the primary winding 131,the secondary control circuit 222 synchronously receives the energyinputted to the primary winding 131 via activation of the switchcircuitry 232 between times Y22 and Y23. The secondary control circuitry222 delivers the energy received through the secondary winding 132 toload 118 and/or output capacitor 210.

Further in this example embodiment, the primary control circuit 221receives feedback 142 around time Y31. The feedback 142 is a request foradditional energy.

In response to receiving the feedback 142 indicating that the secondarycontrol circuitry 222 needs more energy to maintain the output voltage190, the primary control circuit 221 stops the timer 1210 and comparesthe corresponding time value of 8.0 μs to the setpoint time value 1230(10 μs). In this example embodiment, in response to detecting that thetime 8.0 μs is still less than the setpoint time value 1230, the primarycontrol circuit 221 increases the pulse duration of energizing theprimary winding 131 on the cycle Y+2 with respect to a magnitude of thepulse duration of energizing the primary winding on the cycle Y+1. Morespecifically, in response to receiving the feedback 142 just before timeY31, the primary control circuitry 221 energizes the primary winding 131between time Y31 and time Y32 (100 nS) to accommodate, for example, anincreased consumption of power by load 118.

In this manner, the primary control circuit 221 can increase a durationof energizing the primary winding 131 cycle over cycle to accommodatepower consumption by the dynamic load 118.

In one embodiment, note that the primary control circuit 221 candiscontinue increasing a pulse duration of energizing the primarywinding 131 and merely operate in a fixed pulse, variable frequencymode. In such an instance, the pulse duration of energizing the primarywinding is set or increased to a maximum fixed value. The frequency ofoperation depends upon the timing of receiving feedback from thesecondary control circuit 222 requesting additional energy. This is moreparticularly shown in FIG. 17.

As shown in FIG. 17, for cycle Z1, the primary control circuit 221activates the primary winding 131 for a duration of 250 ns. The primarycontrol circuit 221 receives a feedback request for more energy throughthe primary winding 131 at a time of 8 μs after starting the timer 1210at the beginning of cycle Z1. The secondary control circuit 221generates the feedback 142 in response to detecting that the magnitudeof the output voltage falls below a threshold value or that an error ofthe output voltage 190 with respect to a reference is greater than athreshold value.

In response to receiving such feedback at the end of cycle Z1 (8 μslater), the primary control circuit 221 immediately activates theprimary winding 131 for 250 nanoseconds at the start of cycle Z2.

Subsequent to activating the primary winding 131 at the beginning ofcycle Z2, the primary control circuit 221 receives feedback fromsecondary control circuit 222 for more energy 6 μs after starting thetimer 1210 at the beginning of cycle Z2. The secondary control circuit222 generates the feedback in response to detecting a trigger event suchas that the magnitude of the output voltage 190 falls below a thresholdvalue. In response to receiving the feedback at the end of cycle Z2 (6μs), the primary control circuit 221 immediately activates the primarywinding 131 for 250 nanoseconds at the start of cycle Z3.

Subsequent to activating the primary winding 131 at the beginning ofcycle Z3, the primary control circuit 221 receives feedback fromsecondary control circuit 222 for more energy 6 μs after starting thetimer 1210 at the beginning of cycle Z3. The secondary control circuit222 generates the feedback in response to detecting that the magnitudeof the output voltage 190 falls below a threshold value. In response toreceiving the feedback at the end of cycle Z3 (6 μs), the primarycontrol circuit 221 immediately activates the primary winding 131 for250 nanoseconds at the start of cycle Z4.

Subsequent to activating the primary winding 131 at the beginning ofcycle Z4, the primary control circuit 221 receives feedback fromsecondary control circuit 222 for more energy 7.5 μs after starting thetimer 1210 at the beginning of cycle Z4. In response to receiving thefeedback at the end of cycle Z4 (7.5 μs), the primary control circuit221 immediately activates the primary winding 131 for 250 nanoseconds atthe start of cycle Z5.

Subsequent to activating the primary winding 131 at the beginning ofcycle Z5, the primary control circuit 221 receives feedback fromsecondary control circuit 222 for more energy 8 μs after starting thetimer 1210 at the beginning of cycle Z5. In response to receiving thefeedback at the end of cycle Z5 (8 μs), the primary control circuit 221immediately activates the primary winding 131 for 250 nanoseconds at thestart of cycle Z5.

Accordingly, while in the second mode (variable frequency mode), theprimary control circuit 221 can be configured to set a pulse duration ofenergizing the primary winding 131 to be substantially constant. Theprimary control circuit 221 varies a frequency of energizing the primarywinding 131 over each of the multiple cycles depending on times ofreceiving the feedback request for additional energy.

FIG. 18 is an example diagram illustrating modification of a pulse widthin response to receiving feedback according to embodiments herein.

In this example embodiment, the secondary control circuit 222 providesfeedback early in a respective cycle. In response to detecting thefeedback 142 early in the cycle, the primary control circuit 221substantially increases a pulse duration of activating the primarywinding 131 on a subsequent cycle. For example, initially, the primarycontrol circuit 221 sets the ON time of switch circuitry 231 to be 50 nSbetween time X11 and X12. In response to receiving feedback 142 so earlyin the cycle (such as at 5 uS instead of 10 uS), the primary controlcircuit 221 controls a pulse duration of energizing the primary winding131 to be 100 nS.

FIG. 19 is an example diagram illustrating modification of a pulse widthin response to receiving feedback according to embodiments herein.

In this example embodiment, the secondary control circuit 222 providesfeedback 142 including state information indicating one of multiplelevels detected by the secondary control circuit 222. The feedback 142can indicate any suitable information such as a magnitude of an errorbetween the output voltage 190 and a reference voltage, an amount bywhich to increase a pulse duration of activating the primary winding131, etc.

In response to receiving the feedback 142, and in accordance with thefeedback 142, the primary control circuit 221 modifies the pulseduration for a subsequent cycle. For example, initially, the primarycontrol circuit 221 sets the ON time of switch circuitry 231 to be 50 nSbetween time Y21 and Y22. In response to receiving feedback 142, andassuming that the feedback 142 indicates to add 200 nS to the pulseduration over a prior cycles pulse duration, the primary control circuit221 adds 200 nS to 50 nS to set the pulse duration between Y31 and Y32to be 250 nS.

FIG. 20 is an example diagram illustrating use of multi-state feedbackto control an output voltage according to embodiments herein.

In this example embodiment, the secondary control circuit 222 generatesthe feedback 142 to include state information (such as H3, H2, H1, N,L1, L2, or L3). In other words, for each respective cycle, the feedback142 indicates a particular state selected amongst multiple possiblestates (such as H3, H2, H1, N, L1, L2, or L3); each of the statesindicates a degree to which a measured magnitude of the output voltage190 differs from a desired setpoint reference voltage.

As shown, in cycle A1, based on monitoring the output voltage 190, thesecondary control circuit 222 generates feedback 142-1. Because thesecondary control circuit 222 detects that the voltage falls within thenominal range at a respective sample time, the secondary control circuit222 produces the feedback 142-1 to include state information N(ominal).This notifies the primary control circuit 221 to activate the primarywinding 131 on cycle A2 using the same pulse width as a prior cycle.There is no need to increase the pulse width because the voltage iswithin the nominal range. Based on the received feedback 142-1, at thebeginning of cycle A2, the primary control circuit 221 activates theprimary winding 131 for 100 ns.

In cycle A2, based on monitoring the output voltage 190, the secondarycontrol circuit 222 generates feedback 142-2. Because the secondarycontrol circuit 222 detects that the voltage falls within the L3 rangeat a time of sampling (meaning that the magnitude of the output voltage190 is very low due to a transient load condition), the secondarycontrol circuit 222 produces the feedback 142-2 to include stateinformation L3, notifying the primary control circuit to (that themagnitude of the output voltage 190 is too low and to) increase a pulsewidth of activating the primary winding 131 with respect to the previouscycle. The secondary control circuit 222 inputs the feedback 142-2 intothe secondary winding 132 for receipt by the primary control circuit 221over the primary winding 131.

In one embodiment, the primary control circuit 221 maps the stateinformation L3 to a suitable adjustment value of 150 nS. Based on thereceived feedback 142-2, at the beginning of subsequent cycle A3, theprimary control circuit 221 activates the primary winding 131 for andadditional 150 nS over the prior cycle. In other words, the primarycontrol circuit 221 activates the primary winding 135 for 250nanoseconds at the beginning of cycle A3. This increased amount ofenergy inputted to the primary winding 131 at the beginning of cycle A3helps to increase the magnitude of the output voltage 190 back to ornear the nominal range.

In cycle A3, based on monitoring the output voltage 190, the secondarycontrol circuit 222 generates feedback 142-3. Because the secondarycontrol circuit 222 detects that the voltage falls within the L1 rangeat a time of sampling (meaning that the magnitude of the output voltage190 is still low due to the transient load condition), the secondarycontrol circuit 222 produces the feedback 142-3 to include stateinformation L1, notifying the primary control circuit 221 to increase apulse width of activating the primary winding 131 with respect to theprevious cycle. The secondary control circuit 222 inputs the feedback142-3 into the secondary winding 132 for receipt by the primary controlcircuit 221 over the primary winding 131.

In accordance with further embodiments, the primary control circuit 221maps the state information L1 to a suitable adjustment value such as 50nS. Based on the received feedback 142-3, at the beginning of cycle A4,the primary control circuit 221 activates the primary winding 131 for anadditional 50 nS over the prior cycle. In other words, the primarycontrol circuit 221 activates the primary winding 135 for 300nanoseconds at the beginning of cycle A4. This increased amount ofenergy inputted to the primary winding 131 at the beginning of cycle A4helps to increase the magnitude of the output voltage 190 back to ornear the nominal range.

Further in cycle A4, based on monitoring the output voltage 190, thesecondary control circuit 222 generates feedback 142-4. Because thesecondary control circuit 222 detects that the voltage falls within thenominal range again, the secondary control circuit 222 produces thefeedback 142-4 to include state information N(ominal), notifying theprimary control circuit 221 to activate the primary winding 131 usingthe same pulse width as a prior cycle. In this instance, there is noneed to increase the pulse width because the voltage is within thenominal range. Based on the received feedback 142-4, at the beginning ofcycle A5, the primary control circuit 221 activates the primary winding131 for 300 ns (no change from the last cycle).

In this manner, the multi-state information can be conveyed as feedbackover the respective secondary winding 130 to the primary winding 131 tonotify the primary control circuit 221 how to control a pulse width ofactivating the primary winding 131 on a subsequent cycle.

FIG. 21 is an example diagram illustrating use of multi-state feedbackto control an output voltage according to embodiments herein.

In this example embodiment, the secondary control circuit 222 generatesthe feedback 142 to include state information (such as H3, H2, H1, N,L1, L2, or L3). In other words, for each respective cycle, the feedback142 indicates a particular state selected amongst multiple possiblestates (such as H3, H2, H1, N, L1, L2, or L3); each of the statesindicates a degree to which a measured magnitude of the output voltage190 differs from a desired setpoint reference voltage.

As shown, in cycle B1, based on monitoring the output voltage 190, thesecondary control circuit 222 generates feedback 142-1. Because thesecondary control circuit 222 detects that the voltage falls within thenominal range at a respective sample time, the secondary control circuit222 produces the feedback 142-1 to include state information N(ominal).This notifies the primary control circuit 221 to activate the primarywinding 131 on cycle B2 using the same pulse width as a prior cycle.There is no need to increase the pulse width because the voltage iswithin the nominal range. Based on the received feedback 142-1, at thebeginning of cycle B2, the primary control circuit 221 activates theprimary winding 131 for 100 ns.

In cycle B2, based on monitoring the output voltage 190, the secondarycontrol circuit 222 generates feedback 142-2. Because the secondarycontrol circuit 222 detects that the voltage falls within the H3 rangeat a time of sampling (meaning that the magnitude of the output voltage190 is very high due to a transient load condition), the secondarycontrol circuit 222 produces the feedback 142-2 to include stateinformation H3, notifying the primary control circuit to (that themagnitude of the output voltage 190 is too low and to) decrease a pulsewidth of activating the primary winding 131 with respect to the previouscycle. The secondary control circuit 222 inputs the feedback 142-2 intothe secondary winding 132 for receipt by the primary control circuit 221over the primary winding 131.

In one embodiment, the primary control circuit 221 maps the stateinformation H3 to a suitable adjustment value of −150 nS. Based on thereceived feedback 142-2, at the beginning of subsequent cycle B3, theprimary control circuit 221 activates the primary winding 131 for 150 nSless time over the prior cycle. In other words, the primary controlcircuit 221 activates the primary winding 135 for 150 nanoseconds at thebeginning of cycle B3. This decreased amount of energy inputted to theprimary winding 131 at the beginning of cycle B3 helps to increase themagnitude of the output voltage 190 back to or near the nominal range.

In cycle B3, based on monitoring the output voltage 190, the secondarycontrol circuit 222 generates feedback 142-3. Because the secondarycontrol circuit 222 detects that the voltage falls within the H1 rangeat a time of sampling (meaning that the magnitude of the output voltage190 is still high due to the transient load condition), the secondarycontrol circuit 222 produces the feedback 142-3 to include stateinformation H1, notifying the primary control circuit 221 to increase apulse width of activating the primary winding 131 with respect to theprevious cycle. The secondary control circuit 222 inputs the feedback142-3 into the secondary winding 132 for receipt by the primary controlcircuit 221 over the primary winding 131.

In accordance with further embodiments, the primary control circuit 221maps the state information H1 to a suitable adjustment value such as −50nS. Based on the received feedback 142-3, at the beginning of cycle B4,the primary control circuit 221 activates the primary winding 131 for 50nS less than over the prior cycle. In other words, the primary controlcircuit 221 activates the primary winding 135 for 100 nanoseconds at thebeginning of cycle B4. This decreased amount of energy inputted to theprimary winding 131 at the beginning of cycle B4 helps to decrease themagnitude of the output voltage 190 back to or near the nominal range.

Further in cycle B4, based on monitoring the output voltage 190, thesecondary control circuit 222 generates feedback 142-4. Because thesecondary control circuit 222 detects that the output voltage 190 fallswithin the nominal range again, the secondary control circuit 222produces the feedback 142-4 to include state information N(ominal),notifying the primary control circuit 221 to activate the primarywinding 131 using the same pulse width as a prior cycle. In thisinstance, there is no need to adjust the pulse width because the voltageis within the nominal range. Based on the received feedback 142-4, atthe beginning of cycle B5, the primary control circuit 221 activates theprimary winding 131 for 100 ns (no change from the last cycle).

In this manner, the multi-state information can be conveyed as feedbackover the respective secondary winding 130 to the primary winding 131 tonotify the primary control circuit 221 how to control a pulse width ofactivating the primary winding 131 on a subsequent cycle.

Accordingly, the use of different levels of state information in thefeedback 142 serves to provide a fast loop in which to modify the pulseduration to the appropriate value. In one embodiment, smallermodifications to the pulse duration over time (as previously discussed)based on comparison of the actual frequency 1108 to a desired frequency1120 is a slower loop, that also makes adjustments to the pulse durationcycle after cycle to maintain the output voltage 190.

FIG. 22 is an example diagram illustrating of using multi-state feedbackaccording to embodiments herein.

In this example embodiment, similar to as discussed above for FIGS. 20and 21, the primary control circuit 221 receives level information inrespective feedback 142. However, in this embodiment, the primarycontrol circuit 221 uses the feedback to temporarily adjust the pulseduration of energizing the primary winding 131.

For example, in response to receiving state information L3 at the end ofcycle D2, the primary control circuit 221 temporarily increases thepulse by a corresponding time duration of 150 nS. Accordingly, at thebeginning of cycle D3, the primary control circuit 221 activates switchcircuitry 231 for an additional 150 nS with respect to the last cycle.In other words, the primary control circuit 221 energizes the primarywinding 131 for 250 nS.

In the following cycle Z3, in response to receiving state information L1at the end of cycle D3, the primary control circuit 221 temporarilyincreases the pulse by a corresponding time duration of 50 nS.Accordingly, at the beginning of cycle D4, the primary control circuit221 activates switch circuitry 231 for an additional 50 nS with respectto the original pulse time of power converter circuit 100 nS. In otherwords, the primary control circuit 221 energizes the primary winding 131for 150 nS.

In the following cycle D4, in response to receiving state information Nat the end of cycle Z4, the primary control circuit 221 makes no changesto the pulse duration f power converter circuit 100 nS. Accordingly, atthe beginning of cycle D5, the primary control circuit 221 activatesswitch circuitry 231 for power converter circuit 100 nS.

Accordingly, the level information received in the feedback 142 can beused to indicate a temporary amount to modify the pulse durations ofenergizing the primary winding 131. As previously discussed, note thatthe slow loop adjustments continue to operate in a background to modifythe rate and/or duration of energizing the primary winding 135.

Functionality supported by the different resources will now be discussedvia flowcharts in FIGS. 23-26. Note that the steps in the flowchartsbelow can be executed in any suitable order.

FIG. 23 is a flowchart 2300 illustrating an example method according toembodiments. Note that there will be some overlap with respect toconcepts as discussed above.

In processing operation 2310, the primary circuit 121 operates powerconverter circuit 100 to input energy to primary winding 131 of atransformer circuitry 130 and subsequently receive the energy through asecondary winding 132 of the transformer circuitry 130 over each ofmultiple cycles. The power converter circuit 100 produces an outputvoltage 190 using the energy received through the secondary winding 132.

In processing operation 2320, over a range of different magnitudes ofpower delivered by the output voltage 190 to a dynamic load 118, thepower converter circuit 100 switches modal operation between a firstmode and a second mode based on a timing of receiving feedback 142(indicating a request for more energy) conveyed from the secondarywinding 132 to the primary winding 131 over each of multiple cycles.

In sub-processing operation 2330, in the first mode, when the dynamicload consumes current from the output voltage 190 below a thresholdvalue, the primary circuit 121 adjusts the pulse durations of energizingthe primary winding 131 over multiple cycles to cause the frequency ofenergizing the primary winding 131 to be substantially equal to adesired frequency setpoint.

In sub-processing operation 2340, in the second mode, the primarycircuit 121 varies a frequency of energizing the primary winding 131over each of the multiple cycles depending on times of receiving thefeedback 142.

FIG. 24 is a flowchart 2400 illustrating an example method according toembodiments herein. Note that there will be some overlap with respect toconcepts as discussed above.

In processing operation 2410, the primary circuit 121 controls input ofenergy to a primary winding 131 of the transformer circuitry 130. Thesecondary circuit 122 controls receipt of energy through the secondarywinding 132 of the transformer circuitry 130.

In processing operation 2420, the primary circuit 121 produces an outputvoltage 190 using the energy received through the secondary winding 132.

In processing operation 2430, the secondary circuit 121 varies a timingof conveying feedback 142 (with respect to times of receiving energythrough the secondary winding 132) to the primary circuit 121 overmultiple cycles to maintain a magnitude of the output voltage 190 withina desired range.

FIGS. 25 and 26 combine to form a flowchart 2500 (e.g., 2500-1 and2500-2) illustrating an example method according to embodiments. Notethat there will be some overlap with respect to concepts as discussedabove.

In processing operation 2510 of FIG. 25, the primary circuit 121controls input of energy to the primary winding 131 of a transformercircuitry 130. The secondary circuit 122 controls receipt of energythrough the secondary winding 132 of the transformer circuitry 130.

In processing operation 2520, the secondary circuit 122 produces anoutput voltage 190 using the energy received through the secondarywinding 132.

In processing operation 2530, during a cycle of inputting energy to theprimary winding and receiving the energy through the secondary winding:i) the primary circuit 121 starts a timer to track passage of time inoperation 1540, ii) the primary circuit 121 uses the timer to monitor atime of receiving the feedback 142 through the primary winding 131 insub-operation 2550.

In processing operation 2610 of FIG. 26, the secondary circuit 122controls a timing of conveying feedback 142 through the secondarywinding 132 to the primary winding 131 to maintain a magnitude of theoutput voltage 190 within a desired range. In one embodiment, inprocessing operation 1620, the secondary circuit 122 delays a timing ofconveying the feedback 142 through the secondary winding 132 to theprimary winding 131 until a time of detecting that the magnitude of theoutput voltage 190 crosses (such as falls below) a threshold value.

In processing operation 2630, using the timer, the primary circuit 121compares the time of receiving the feedback 142 to a setpoint timevalue. The setpoint time value corresponds to a desired fixed frequencyof inputting quanta of energy into the primary winding over multiplecycles.

In processing operation 2640, depending on results of the comparison,the primary circuit 121 adjusts a magnitude of a pulse duration ofenergizing the primary winding 131 on a next cycle with respect to amagnitude of a pulse duration of energizing the primary winding 131 onthe previous cycle.

In sub-processing operation 2650, in response to detecting that the timeis greater than the setpoint time value, the primary circuit 121decreases the pulse duration of energizing the primary winding 131 onthe second cycle with respect to a magnitude of the pulse duration ofenergizing the primary winding 131 on the first cycle.

In processing operation 2660, in response to detecting that the time isless than the setpoint time value, the primary circuit 121 increases thepulse duration of energizing the primary winding 131 on the second cyclewith respect to a magnitude of the pulse duration of energizing theprimary winding 131 on the first cycle.

FIG. 27 is an example timing diagram illustrating control of providingfeedback through the secondary winding to the primary winding accordingto embodiments herein.

As shown in timing diagram 2705, further embodiments herein can includeimplementing QZVS (Quasi Zero Voltage Switching) or ZVS (Zero VoltageSwitching) in the secondary circuit 122 when providing feedback to theprimary controller 221.

For example, as previously discussed, the secondary controller 222controls switch circuitry 132 to convey communications (via a requestpulse through the secondary winding 132 and, consequently, the primarywinding 131) to the primary controller 221. The feedback can include anysuitable information. In one embodiment, the feedback indicates thesecondary controller 222 needs more energy to maintain the outputvoltage 190 within regulation.

As shown in timing diagram 2705, at time T2702, the secondary controller222 can initiate activation of switch circuitry 232 to communicate withthe primary controller 221. If the time of activating the switchcircuitry 232 is random, at time T2701, the respective voltage of thedrain node of switch circuitry 232 may be substantially greater than 10Volts. In such an instance, this results in extra unnecessary powerconsumption over time. In other words, activating the switch circuitry232 to an ON state when the voltage of the drain node is substantiallyabove 5-10 volts to provide feedback causes the switch circuitry 232 toconsume this energy.

To provide better efficiency, embodiments herein include adding aresource such as comparator 2710 to the secondary circuit 122 to monitorthe voltage (i.e., voltage VDS) at the drain node across the switchcircuitry 232. In one embodiment, when the voltage VDS is below arespective chosen threshold value, for instance 3 or 7 volts, and thesecondary controller 222 needs to generate feedback such as to requestmore power in the forward direction from primary winding 131 tosecondary winding 132, the secondary controller 222 activates switchcircuitry 232 to create the request pulse (feedback) at the appropriatetime. Note that if the voltage VDS is above the threshold value, thecontroller circuitry 222 can be configured to delay when the requestpulse is generated. In other words, in accordance with yet furtherembodiments, as previously discussed, it is possible that the voltage atthe drain node of the switch circuitry 232 is above the comparatorthreshold voltage value when (such as at time T2702) the secondarycontroller 222 attempts to communicate the feedback to the primarycontroller 221. In such an instance, the secondary controller 222 can beconfigured to delay timing of conveying the feedback through thesecondary winding 132 to the primary winding 131 until a time (such asuntil time T2703) which corresponds to detecting that the magnitude ofthe monitored voltage (such as VDS of switch circuitry 232) is below athreshold value. Thus, the comparator 2710 can be used to determine anappropriate time to activate switch circuitry 232 to an ON state toprovide feedback.

Note that the delay of activating the switch circuitry 232 to create thecorresponding feedback may be substantially shorter when the load 118consumes a higher amount of current. Conversely, the delay of activatingthe switch circuitry 232 to create corresponding feedback may besubstantially longer when the load 118 consumes less current.

In accordance with further embodiments, the operations of communicatingthe feedback through the secondary winding 132 to the primary winding131 can include: comparing a voltage level of a node of the secondarywinding 132 (such as the node of the secondary winding 132 connected tothe drain node of the switch circuitry 232) to a threshold value; andcontrolling timing of conveying the feedback through the secondarywinding 132 to the primary winding 131 to occur when the voltage levelof the node of the secondary winding is below the threshold value (suchas a threshold value setting of between 0-7 volts). In this manner,embodiments herein include ZVS operation and/or quasi-ZVS operation whencommunicating feedback in a reverse direction through transformercircuitry 130 back to the primary controller 221.

FIG. 28 is a timing diagram illustrating overcurrent protection providedby the power converter circuit 100 according to embodiments herein.

As previously discussed, FIGS. 11-26 and corresponding text discussvariable ON-time control via power converter circuit 100 to providedifferent feedback through the windings of the transformer circuitry 130back to the primary controller 221.

In accordance with further embodiments herein, the primary controller221 is configured to limit how much power is conveyed from the primarywinding 131 to the secondary winding 132. Limiting a rate of forwardingenergy through the primary winding 131 to the secondary winding 132 toproduce the output voltage 190 prevents damage to the power convertercircuit 100 and potentially prevents damage to the load 118.

In this example embodiment, at time T2801 of timing diagram 2805, assumethat an overcurrent event occurs during which the load 118 (or otherentity) consumes more power than the primary controller 221 is able toconvey from the primary winding 131 through the secondary winding 132.In such an instance, when operating at maximum load, as previouslydiscussed with respect to FIG. 12, the power converter circuit 100operates in mode #2 (variable frequency mode) because the load 118consumes maximum power.

Further in this example, assume that the maximum load currentconsumption is 3.2 Amperes and that the overcurrent protection providedby the power converter circuit 100 limits the current through thesecondary winding 132 such that the output voltage 190 provides amaximum of 3.4 Amperes to a respective load 118. In other words, aspreviously discussed, the primary controller 221 is limited as to a rateat which it can input energy into the primary winding 131 to thesecondary winding 132 to power the load 118. As shown in timing diagram2805, because the current consumed by the load 118 is over a maximumcurrent limit between time T2801 and time T2802, the magnitude of theoutput voltage 190 droops. During the overcurrent condition, such asbetween time T2801 and time T2802, the switching frequency (rate atwhich the primary controller 221 inputs energy into the primary winding131) is relatively constant. Additionally, as shown, between time T2801and time T2802, the magnitude of current IDS2 through the secondarywinding 132 and provided to the respective load 118 reaches a maximumcurrent limit of 3.4 Amperes.

Subsequent to time T2802, the output voltage 190 recovers toapproximately a regulated output of 20 VDC again.

If desired, the maximum current limit provided by the power convertercircuit 100 can be programmed by an outside resource. For example, powerconverter circuit 100 can be programmed to control a rate of inputtingenergy (over multiple delivery or switching cycles) into the primarywinding 131 to be below a threshold value to limit an amount of currentthat the output voltage 190 is able to supply to a respective load.Thus, the power converter circuit 100 is protected from being damagedduring unusually heavy load conditions caused by failures.

Based on the description set forth herein, numerous specific detailshave been set forth to provide a thorough understanding of claimedsubject matter. However, it will be understood by those skilled in theart that claimed subject matter may be practiced without these specificdetails. In other instances, methods, apparatuses, systems, etc., thatwould be known by one of ordinary skill have not been described indetail so as not to obscure claimed subject matter. Some portions of thedetailed description have been presented in terms of algorithms orsymbolic representations of operations on data bits or binary digitalsignals stored within a computing system memory, such as a computermemory. These algorithmic descriptions or representations are examplesof techniques used by those of ordinary skill in the data processingarts to convey the substance of their work to others skilled in the art.An algorithm as described herein, and generally, is considered to be aself-consistent sequence of operations or similar processing leading toa desired result. In this context, operations or processing involvephysical manipulation of physical quantities. Typically, although notnecessarily, such quantities may take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared orotherwise manipulated. It has been convenient at times, principally forreasons of common usage, to refer to such signals as bits, data, values,elements, symbols, characters, terms, numbers, numerals or the like. Itshould be understood, however, that all of these and similar terms areto be associated with appropriate physical quantities and are merelyconvenient labels. Unless specifically stated otherwise, as apparentfrom the following discussion, it is appreciated that throughout thisspecification discussions utilizing terms such as “processing,”“computing,” “calculating,” “determining” or the like refer to actionsor processes of a computing platform, such as a computer or a similarelectronic computing device, that manipulates or transforms datarepresented as physical electronic or magnetic quantities withinmemories, registers, or other information storage devices, transmissiondevices, or display devices of the computing platform.

Further Summary and Permutations Of Embodiments

Clause A1. A method comprising:

inputting energy to a primary winding of a transformer;

receiving the energy through a secondary winding of the transformer;

producing an output voltage from the energy received through thesecondary winding; and

communicating feedback through the secondary winding to the primarywinding, the communicated feedback representing state information, thestate information indicating a particular state selected amongstmultiple possible states.

Clause A2. The method as in any of one or more clauses A1, A3-A16,wherein inputting the energy includes controlling a flow of currentthrough the primary winding of the transformer to store the energy inthe transformer;

wherein receiving the energy includes controlling a flow of currentthrough the secondary winding of the transformer to receive the energyand produce the output voltage.

Clause A3. The method as in any of one or more clauses A1-A2, A4-A16further comprising:

comparing a magnitude of the output voltage to a reference voltage; and

producing the feedback to control delivery of subsequent energy inputtedto the primary winding to maintain the magnitude of the output voltagewithin a desired voltage range.

Clause A4. The method as in any of one or more clauses A1-A3, A5-A16further comprising:

controlling a flow of current through the secondary winding tocommunicate the feedback from the primary winding to the secondarywinding; and

monitoring a magnitude of voltage at a node of the primary winding toreceive the feedback.

Clause A5. The method as in any of one or more clauses A1-A4, A6-A16further comprising: controlling a duration of energizing the secondarywinding to produce the feedback.

Clause A6. The method as in any of one or more clauses A1-A5, A7-A16further comprising:

selecting a length of the duration from multiple durations, each of themultiple durations corresponding to a different respective state of themultiple possible states.

Clause A7. The method as in any of one or more clauses A1-A6, A8-A16further comprising:

communicating the feedback through the secondary winding to the primarywinding after conveyance of the energy from the primary winding to thesecondary winding of the transformer.

Clause A8. The method as in any of one or more clauses A1-A7, A9-A16further comprising:

monitoring a magnitude of voltage on a node of the primary winding toreceive the feedback, the magnitude of the monitored voltage indicatingthe state information associated with deriving the output voltage.

Clause A9. The method as in any of one or more clauses A1-A8, A10-A16further comprising:

controlling a magnitude of subsequent energy inputted to the primarywinding to the transformer depending on the magnitude of the monitoredvoltage indicating the state information.

Clause A10. The method as in any of one or more clauses A1-A9, A11-A16,wherein the magnitude of the voltage at the node of the primary windingrepresents a detected peak transition or valley transition of thevoltage at the node occurring within a monitored window of time.

Clause A11. The method as in any of one or more clauses A1-A10, A12-A16further comprising:

utilizing the feedback to determine how to adjust an amount ofsubsequent energy inputted to the primary winding to control a magnitudeof the output voltage to be within a desired range.

Clause A12. The method as in any of one or more clauses A1-A11, A13-A16,further comprising: utilizing the feedback to determine an incrementalamount of additional energy to input to the primary winding on asubsequent cycle.

Clause A13. The method as in any of one or more clauses A1-A12, A14-A16further comprising:

over time, repeatedly receiving feedback communications inputted throughthe secondary winding to the primary winding, the feedbackcommunications indicating a different one of the multiple possiblestates; and

repeatedly adjusting an amount of subsequently inputted energy to theprimary winding over multiple successive delivery cycles depending onthe received feedback communications to control a magnitude of theoutput voltage to be within a desired range.

Clause A14. The method as in any of one or more clauses A1-A13, A15-A16wherein the multiple possible states are selectable commands; and

wherein the state information is a particular command selected from theselectable commands.

Clause A15. The method as in any of one or more clauses A1-A14, A15further comprising:

analyzing the feedback to obtain an error signal associated withproducing the output voltage, the error signal indicating a differencebetween a magnitude of the output voltage and a desired setting of theoutput voltage; and

utilizing the error signal to determine an amount of subsequent energyto input to the primary winding to control a magnitude of the outputvoltage to be within a desired range.

Clause A16. The method as in any of one or more clauses A1-15, whereinthe energy inputted to the primary winding is a first quantum of energyinputted to the primary winding of the transformer, the method furthercomprising:

generating the state information to represent multiple bits of data, thefeedback communicated through the secondary winding to the primarywinding subsequent to receiving the first quantum of energy through thesecondary winding and prior to input of a next quantum of energy intothe primary winding.

Clause A17. An apparatus comprising:

a transformer including a primary winding and a secondary winding;

a primary circuit to control input of energy to the primary winding ofthe transformer;

a secondary circuit to control receiving the energy through thesecondary winding of the transformer and derive an output voltage fromthe received energy; and

the secondary circuit operable to communicate feedback through thesecondary winding to the primary winding, the communicated feedbackincluding state information indicating a particular state selectedamongst multiple possible states.

Clause A18. The apparatus as in any of one or more clauses A17, A19-A33,wherein the primary circuit includes a primary switch, the primarycircuit controlling an ON/OFF state of the primary switch to control aflow of current through the primary winding of the transformer to storethe energy in the transformer; and

wherein the secondary circuit includes a secondary switch, the secondarycircuit controlling an ON/OFF state of the secondary switch to control aflow of current through the secondary winding of the transformer toreceive the energy.

Clause A19. The apparatus as in any of one or more clauses A17-A18,A20-A33, wherein the primary circuit includes a monitor circuit to:

compare a magnitude of the output voltage to a reference voltage; and

produce the feedback to control delivery of subsequent energy inputtedto the primary winding to maintain the magnitude of the output voltagewithin a desired voltage range.

Clause A20. The apparatus as in any of one or more clauses A17-A19,A21-A33, wherein the secondary circuit includes control circuitry tocontrol a flow of current through the secondary winding to communicatethe feedback from the secondary winding to the primary winding; and

wherein the primary circuit includes a monitor circuit to monitor amagnitude of voltage at a node of the primary winding to receive thefeedback.

Clause A21. The apparatus as in any of one or more clauses A17-A20,A22-A33, wherein the secondary circuit includes control circuitry tocontrol a duration of a flow of current through the secondary winding toproduce the state information included in the feedback.

Clause A22. The apparatus as in any of one or more clauses A17-A21,A23-A33, wherein the secondary circuit includes control circuitry to:

select a length of the duration from multiple durations, each of themultiple durations corresponding to a different respective one of themultiple possible states.

Clause A23. The apparatus as in any of one or more clauses A17-A22,A24-A33, wherein the secondary circuit utilizes a portion of thereceived energy to communicate the feedback through the secondarywinding to the primary winding.

Clause A24. The apparatus as in any of one or more clauses A17-A23,A25-A33, wherein the primary circuit includes control circuitry tomonitor a magnitude of voltage on a node of the primary winding toreceive the feedback, the magnitude of the monitored voltage indicatingthe particular state associated with deriving the output voltage.

Clause A25. The apparatus as in any of one or more clauses A17-A24,A26-A33, wherein the primary circuit includes control circuitry to:

control input of subsequent energy inputted through the primary windingto the transformer depending on the magnitude of the monitored voltageindicating the particular state.

Clause A26. The apparatus as in any of one or more clauses A17-A25,A27-A33, wherein the magnitude of the voltage at the node of the primarywinding represents a detected peak transition or valley transition ofthe voltage at the node occurring within a monitored window of time.

Clause A27. The apparatus as in any of one or more clauses A17-A26,A28-A33, wherein the primary circuit includes control circuitry toutilize the feedback to adjust an amount of subsequent energy inputtedto the primary winding to control a magnitude of the output voltage tobe within a desired range.

Clause A28. The apparatus as in any of one or more clauses A17-A27,A29-A33, wherein the control circuit is operable to utilize the feedbackto determine an incremental amount of additional energy to input to theprimary winding on a subsequent cycle.

Clause A29. The apparatus as in any of one or more clauses A17-A28,A30-A33, wherein the primary circuit includes control circuitry to:

over time, repeatedly receive feedback communications inputted throughthe secondary winding, the feedback communications indicating adifferent one of the multiple possible states; and

repeatedly adjust an amount of subsequently inputted energy to theprimary winding over multiple successive delivery cycles depending onthe received feedback communications to control a magnitude of theoutput voltage to be within a desired range.

Clause A30. The apparatus as in any of one or more clauses A17-A29,A31-A33, wherein the multiple possible states are selectable commands;and

wherein the particular state captured by the feedback is a particularcommand selected from the multiple selectable commands.

Clause A31. The apparatus as in any of one or more clauses A17-A31,A32-A33, wherein the secondary circuit is further operable to:

analyze the feedback to obtain an error signal associated with producingthe output voltage; and

utilize the error signal to determine an amount of subsequent energy toinput to the primary winding to control a magnitude of the outputvoltage to be within a desired range.

Clause A32. The apparatus as in any of one or more clauses A17-A31, A33,wherein the energy inputted to the primary winding is a first quantum ofenergy inputted to the primary winding of the transformer; and

wherein the state information in the feedback is encoded to representmultiple bits of data, the feedback communicated through the secondarywinding to the primary winding subsequent to receiving the first quantumof energy through the secondary winding and prior to input of a nextquantum of energy into the primary winding.

Clause A33. The apparatus as in any of one or more clauses A17-A32,wherein the primary circuit is powered with respect to a first groundreference voltage; and

wherein the secondary circuit is powered with respect to a second groundreference voltage, the primary circuit electrically isolated from thesecondary circuit via the transformer.

Clause A34. Computer-readable storage media having instructions storedthereon for processing data information, such that the instructions,when carried out by computer processor hardware, cause the computerprocessor hardware to perform operations of:

controlling input of energy to a primary winding of a transformer;

controlling receipt of the energy through a secondary winding of thetransformer to produce an output voltage; and

communicating feedback through the secondary winding to the primarywinding, the communicated feedback representing state information, thestate information indicating a particular state amongst multiplepossible states.

Clause A35. The method as in any of clauses A1-A16, whereincommunicating the feedback through the secondary winding to the primarywinding includes:

comparing a voltage level of a node of the secondary winding to athreshold value; and

controlling timing of conveying the feedback through the secondarywinding to the primary winding to occur when the voltage level of thenode of the secondary winding is below the threshold value.

Clause A36. The method as in any of clauses A1-A16, whereincommunicating the feedback through the secondary winding to the primarywinding includes:

delaying timing of conveying the feedback through the secondary windingto the primary winding until a time of detecting that the magnitude of amonitored voltage is below a threshold value.

Clause A37. The apparatus as in any of clauses A17-A33, wherein theprimary circuit is operable to control a rate of inputting energy intothe primary winding to be below a threshold value to limit an amount ofcurrent that the output voltage supplies to a respective load.

Clause B1. A method comprising:

controlling operation of a power converter circuit to input energy to aprimary winding of a transformer and receive the energy through asecondary winding of the transformer;

producing an output voltage using the energy received through thesecondary winding; and

controlling a timing of conveying feedback through the secondary windingto the primary winding to maintain a magnitude of the output voltagewithin a desired range.

Clause B2. The method as in any of one or more clauses B1, B3-B15,wherein controlling the timing includes:

delaying the timing of conveying the feedback through the secondarywinding to the primary winding until a time of detecting that themagnitude of the output voltage crosses a threshold value.

Clause B3. The method as in any of one or more clauses B1-B2, B4-B15,wherein controlling the timing includes:

monitoring the magnitude of the output voltage; and

in response to detecting that the magnitude of the output voltagediffers with respect to a setpoint reference voltage above a thresholddifference value, communicating the feedback through the secondarywinding to the primary winding.

Clause B4. The method as in any of one or more clauses B1-B3, B5-B15further comprising:

in response to receiving the feedback, adjusting a pulse duration ofenergizing the primary winding on a subsequent cycle.

Clause B5. The method as in any of one or more clauses B1-B4, B6-B15,wherein controlling operation of the power converter circuit furthercomprises:

controlling a flow of current through the primary winding of thetransformer to store the energy in the transformer; and

subsequent to completion of inputting the energy through the primarywinding, controlling a flow of current through the secondary winding ofthe transformer to receive the energy and produce the output voltage.

Clause B6. The method as in any of one or more clauses B1-B5, B7-B15further comprising:

adjusting a frequency of inputting energy into the primary winding overmultiple cycles depending on times of receiving the feedback; and

in response to detecting the input of the energy into the primarywinding, synchronously receiving the energy via control of currentthrough the secondary winding.

Clause B7. The method as in any of one or more clauses B1-B6, B8-B15further comprising:

during a first cycle of inputting energy to the primary winding andreceiving the energy through the secondary winding:

starting a timer to track passage of time; and

using the timer to determine a time of receiving the feedback at theprimary winding.

Clause B8. The method as in any of one or more clauses B1-B7, B9-B15further comprising:

decreasing the pulse duration of energizing the primary winding on asecond cycle with respect to a magnitude of a pulse duration ofenergizing the primary winding on the first cycle to maintain frequencyoperation of energizing the primary winding over multiple cycles to beabove a frequency threshold value.

Clause B9. The method as in any of one or more clauses B1-B8, B10-B15further comprising:

comparing the time to a setpoint time value, the setpoint time valuecorresponding to a desired fixed frequency of inputting energy into theprimary winding over multiple cycles; and

depending on the comparison, adjusting a magnitude of a pulse durationof energizing the primary winding on a second cycle with respect to amagnitude of a pulse duration of energizing the primary winding on thefirst cycle.

Clause B10. The method as in any of one or more clauses B1-B9, B11-B15,wherein adjusting the magnitude further comprises:

in response to detecting that the time is less than the setpoint timevalue, increasing the pulse duration of energizing the primary windingon the second cycle with respect to a magnitude of the pulse duration ofenergizing the primary winding on the first cycle.

Clause B11. The method as in any of one or more clauses B1-B10, B12-B15,wherein adjusting the magnitude further comprises:

in response to detecting that the time is greater than the setpoint timevalue, decreasing the pulse duration of energizing the primary windingon the second cycle with respect to a magnitude of the pulse duration ofenergizing the primary winding on the first cycle.

Clause B12. The method as in any of one or more clauses B1-B11, B13-B15further comprising:

comparing the time of receiving the feedback at the primary winding to asetpoint time value, the setpoint time value corresponding to a desiredfixed frequency of inputting energy into the primary winding overmultiple cycles; and

in response to detecting that the time is substantially equal to thesetpoint time value, setting a magnitude of the pulse duration ofenergizing the primary winding on the second cycle to be substantiallythe same as a pulse duration of energizing the primary winding on thefirst cycle.

Clause B13. The method as in any of one or more clauses B1-B12, B14-B15,wherein the feedback includes state information indicating a particularstate selected amongst multiple possible states, the feedback varyingdepending on a magnitude of error between the output voltage and adesired setpoint.

Clause B14. The method as in any of one or more clauses B1-B13, B15further comprising:

utilizing the feedback to determine a magnitude in which to adjust apulse duration of energizing the primary winding for a subsequent cycleof energizing the primary winding.

Clause B15. The method as in any of one or more clauses B1-B14 furthercomprising:

producing a difference value indicating a time difference between thetime of receiving the feedback and a setpoint time value, the setpointtime value corresponding to a desired fixed frequency of inputtingenergy into the primary winding over multiple cycles; and

using the difference value to proportionally adjust a magnitude of apulse duration of energizing the primary winding on a second cycle withrespect to a magnitude of a pulse duration of energizing the primarywinding on the first cycle.

Clause B16. An apparatus comprising:

a transformer including a primary winding and a secondary winding;

a primary circuit to control input of energy to the primary winding ofthe transformer;

a secondary circuit to control receiving the energy through thesecondary winding of the transformer and produce an output voltage fromthe received energy; and

the secondary circuit operable to control a timing of conveying feedbackthrough the secondary winding to the primary winding to maintain amagnitude of the output voltage within a desired range.

Clause B17. The apparatus as in any of one or more clauses B16, B18-B30,wherein the secondary circuit delays the timing of conveying thefeedback through the secondary winding to the primary winding until atime of detecting that the magnitude of the output voltage crosses athreshold value.

Clause B18. The apparatus as in any of one or more clauses B16-17,B19-B30, wherein the secondary circuit is operable to:

monitor the magnitude of the output voltage; and

in response to detecting that the magnitude of the output voltagediffers with respect to a setpoint reference voltage above a thresholddifference value, communicate the feedback through the secondary windingto the primary winding.

Clause B19. The apparatus as in any of one or more clauses B16-18,B20-B30, wherein the primary circuit adjusts a pulse duration ofenergizing the primary winding on a subsequent cycle in response toreceiving the feedback.

Clause B20. The apparatus as in any of one or more clauses B16-19,B21-B30, wherein the primary circuit is operable to control a flow ofcurrent through the primary winding of the transformer to store theenergy in the transformer; and

wherein the secondary circuit is operable to control a flow of currentthrough the secondary winding of the transformer to receive the energyand produce the output voltage subsequent to completion of inputting theenergy through the primary winding.

Clause B21. The apparatus as in any of one or more clauses B16-20,B22-B30, wherein the primary circuit is operable to adjust a frequencyof inputting energy into the primary winding over multiple cyclesdepending on times of receiving the feedback; and

wherein the secondary circuit is operable to, in response to detectingthe input of the energy into the primary winding, synchronously receivethe energy via control of current through the secondary winding.

Clause B22. The apparatus as in any of one or more clauses B16-21,B23-B30, wherein the primary circuit includes a timer, the primarycircuit further operable to:

during a first cycle of inputting energy to the primary winding andreceiving the energy through the secondary winding:

start a timer to track passage of time; and

use the timer to determine a time of receiving the feedback at theprimary winding.

Clause B23. The apparatus as in any of one or more clauses B16-22,B24-B30, wherein the primary circuit is further operable to decrease thepulse duration of energizing the primary winding on a second cycle withrespect to a magnitude of a pulse duration of energizing the primarywinding on the first cycle to maintain frequency operation of energizingthe primary winding over multiple cycles to be above a frequencythreshold value.

Clause B24. The apparatus as in any of one or more clauses B16-23,B25-B30, wherein the primary circuit is further operable to:

compare the time to a setpoint time value, the setpoint time valuecorresponding to a desired fixed frequency of inputting energy into theprimary winding over multiple cycles; and

depending on the comparison, adjust a magnitude of a pulse duration ofenergizing the primary winding on a second cycle with respect to amagnitude of a pulse duration of energizing the primary winding on thefirst cycle.

Clause B25. The apparatus as in any of one or more clauses B16-24,B26-B30, wherein the primary circuit is further operable to:

in response to detecting that the time is less than the setpoint timevalue, increase the pulse duration of energizing the primary winding onthe second cycle with respect to a magnitude of the pulse duration ofenergizing the primary winding on the first cycle.

Clause B26. The apparatus as in any of one or more clauses B16-25,B27-B30, wherein the primary circuit is further operable to:

in response to detecting that the time is greater than the setpoint timevalue, decrease the pulse duration of energizing the primary winding onthe second cycle with respect to a magnitude of the pulse duration ofenergizing the primary winding on the first cycle.

Clause B27. The apparatus as in any of one or more clauses B16-26,B28-B30, wherein the primary circuit is further operable to:

compare the time of receiving the feedback at the primary winding to asetpoint time value, the setpoint time value corresponding to a desiredfixed frequency of inputting energy into the primary winding overmultiple cycles; and

in response to detecting that the time is substantially equal to thesetpoint time value, set a magnitude of the pulse duration of energizingthe primary winding on the second cycle to be substantially the same asa pulse duration of energizing the primary winding on the first cycle.

Clause B28. The apparatus as in any of one or more clauses B16-27,B29-B30, wherein the feedback includes state information indicating aparticular state selected amongst multiple possible states, the feedbackvarying depending on a magnitude of error between the output voltage anda desired setpoint.

Clause B29. The apparatus as in any of one or more clauses B16-28, B30,wherein the primary circuit is further operable to utilize the feedbackto determine a magnitude in which to adjust a pulse duration ofenergizing the primary winding for a subsequent cycle of energizing theprimary winding.

Clause B30. The apparatus as in any of one or more clauses B16-29,wherein the primary circuit is further operable to:

produce a difference value indicating a time difference between the timeof receiving the feedback and a setpoint time value, the setpoint timevalue corresponding to a desired fixed frequency of inputting energyinto the primary winding over multiple cycles; and

use the difference value to proportionally adjust a magnitude of a pulseduration of energizing the primary winding on a second cycle withrespect to a magnitude of a pulse duration of energizing the primarywinding on the first cycle.

Clause B31. Computer-readable storage media having instructions storedthereon for processing data information, such that the instructions,when carried out by computer processor hardware, cause the computerprocessor hardware to perform operations of:

controlling operation of a power converter circuit to input energy to aprimary winding of a transformer and receive the energy through asecondary winding of the transformer;

producing an output voltage using the energy received through thesecondary winding; and

controlling a timing of conveying feedback through the secondary windingto the primary winding to maintain a magnitude of the output voltagewithin a desired range.

Clause C1. A method comprising:

operating a power converter circuit to input energy to a primary windingof a transformer and subsequently receive the energy through a secondarywinding of the transformer over multiple cycles, the power convertercircuit producing an output voltage using the energy received throughthe secondary winding; and

switching modal operation of the power converter circuit between a firstmode and a second mode over a range of different magnitudes of powerdelivered by the output voltage to a dynamic load.

Clause C2. The method as in any of one or more clauses C1, C3-C14further comprising:

switching the modal operation of the power converter circuit based onfeedback conveyed from the secondary winding to the primary winding overthe multiple cycles.

Clause C3. The method as in any of one or more clauses C1-C2, C4-C14,wherein the feedback includes state information indicating a particularstate selected amongst multiple possible states, the feedback varyingdepending on a magnitude of error between the output voltage and adesired setpoint.

Clause C4. The method as in any of one or more clauses C1-C3, C5-C14,further comprising:

utilizing state information in the feedback to determine a magnitude inwhich to adjust a pulse duration of energizing the primary winding for asubsequent cycle of energizing the primary winding.

Clause C5. The method as in any of one or more clauses C1-C4, C6-C14,wherein operation of the first mode includes controlling a frequency ofenergizing the primary winding over multiple cycles to be substantiallyconstant; and

wherein operation of the second mode includes varying a frequency ofenergizing the primary winding.

Clause C6. The method as in any of one or more clauses C1-C5, C7-C14,further comprising:

for each of the multiple cycles, receiving the energy and providingfeedback through the secondary winding to the primary winding subsequentto completion of inputting the energy to the primary winding of thetransformer.

Clause C7. The method as in any of one or more clauses C1-C6, C8-C14,further comprising:

while in the first mode, adjusting pulse durations of energizing theprimary winding over multiple cycles; and

while in the second mode, setting a pulse duration of energizing theprimary winding to be substantially constant over multiple cycles.

Clause C8. The method as in any of one or more clauses C1-C7, C9-C14,wherein the first mode includes dynamically adjusting pulse durations ofenergizing the primary winding over the multiple cycles to modify asubsequent frequency of energizing the primary winding; and

wherein the second mode includes varying a frequency of energizing theprimary winding over the multiple cycles depending on times of receivingthe feedback.

Clause C9. The method as in any of one or more clauses C1-C8, C10-C14,further comprising:

in the first mode, adjusting the pulse durations of energizing theprimary winding over multiple cycles to control the frequency ofenergizing the primary winding to be substantially equal to a desiredfrequency setpoint.

Clause C10. The method as in any of one or more clauses C1-C9, C11-C14,further comprising:

when operating in both the first mode and the second mode:

subsequent to receiving a quantum of energy through the secondarywinding to produce the output voltage, delaying a time of conveying afeedback message for a respective cycle through the secondary winding tothe primary winding until a time of detecting that the magnitude of theoutput voltage crosses a threshold value.

Clause C11. The method as in any of one or more clauses C1-C10, C12-C14,wherein the feedback message indicates: i) degradation of the magnitudeof the output voltage, and ii) a request for input of energy into theprimary winding.

Clause C12. The method as in any of one or more clauses C1-C11, C13-C14,further comprising:

switching between the first mode and the second mode depending on atiming of receiving the feedback with respect to a reference time valuein each of the multiple cycles.

Clause C13. The method as in any of one or more clauses C1-C12, C14,further comprising:

during a first cycle of inputting energy to the primary winding andreceiving the energy through the secondary winding:

starting a timer to track passage of time; and

using the timer to determine a time corresponding to receipt of thefeedback at the primary winding.

Clause C14. The method as in any of one or more clauses C1-C13 furthercomprising:

comparing the time to a setpoint time value, the setpoint time valuecorresponding to a minimum desired frequency of inputting energy intothe primary winding over multiple cycles; and

to prevent operation below the minimum desired frequency, while in thefirst mode, using results of the comparison to adjust a magnitude of apulse duration of energizing the primary winding on a second cycle withrespect to a magnitude of a pulse duration of energizing the primarywinding on the first cycle.

Clause C15. An apparatus comprising:

a transformer including a primary winding and a secondary winding;

a primary circuit to control input of energy to the primary winding ofthe transformer;

a secondary circuit to control receiving the energy through thesecondary winding of the transformer and produce an output voltage fromthe received energy; and

the primary circuit operable to switch modal operation of the powerconverter circuit between a first mode and a second mode over a range ofdifferent magnitudes of power delivered by the output voltage to adynamic load.

Clause C16. The apparatus as in clauses C15, C17-C28, wherein theprimary circuit is operable to:

switch the modal operation of the power converter circuit based onfeedback conveyed from the secondary winding to the primary winding overthe multiple cycles.

Clause C17. The apparatus as in any of one or more clauses C15-C16,C18-C28, wherein the feedback includes state information indicating aparticular state selected amongst multiple possible states, the feedbackvarying depending on a magnitude of error between the output voltage anda desired setpoint.

Clause C18. The apparatus as in any of one or more clauses C15-C17,C19-C28, wherein the primary circuit is operable to: utilize stateinformation in the feedback to determine a magnitude in which to adjusta pulse duration of energizing the primary winding for a subsequentcycle of energizing the primary winding.

Clause C19. The apparatus as in any of one or more clauses C15-C18,C20-C28, wherein operation of the first mode includes controlling afrequency of energizing the primary winding over multiple cycles to besubstantially constant; and

wherein operation of the second mode includes varying a frequency ofenergizing the primary winding.

Clause C20. The apparatus as in any of one or more clauses C15-C19,C21-C28, wherein the secondary circuit is further operable to:

for each of the multiple cycles, receive the energy and providingfeedback through the secondary winding to the primary winding subsequentto completion of inputting the energy to the primary winding of thetransformer.

Clause C21. The apparatus as in any of one or more clauses C15-C20,C22-C28, wherein the primary circuit is further operable to:

while in the first mode, adjust pulse durations of energizing theprimary winding over multiple cycles; and

while in the second mode, set a pulse duration of energizing the primarywinding to be substantially constant over multiple cycles.

Clause C22. The apparatus as in any of one or more clauses C15-C21,C23-C28, wherein the first mode includes dynamically adjusting pulsedurations of energizing the primary winding over the multiple cycles tomodify a subsequent frequency of energizing the primary winding; and

wherein the second mode includes varying a frequency of energizing theprimary winding over each of the multiple cycles depending on times ofreceiving the feedback.

Clause C23. The apparatus as in any of one or more clauses C15-C22,C24-C28, wherein the primary circuit is further operable to:

in the first mode, adjust the pulse durations of energizing the primarywinding over multiple cycles to control the frequency of energizing theprimary winding to be substantially equal to a desired frequencysetpoint.

Clause C24. The apparatus as in any of one or more clauses C15-C23,C25-C28, wherein the secondary circuit is further operable to:

when operating in both the first mode and the second mode:

subsequent to receiving energy through the secondary winding to producethe output voltage, delay a time of conveying a feedback message for arespective cycle through the secondary winding to the primary windinguntil a time of detecting that the magnitude of the output voltagecrosses a threshold value.

Clause C25. The apparatus as in any of one or more clauses C15-C24,C26-C28, wherein the feedback message indicates: i) degradation of themagnitude of the output voltage, and ii) a request for input of energyinto the primary winding.

Clause C26. The apparatus as in any of one or more clauses C15-C25,C27-C28, wherein the primary circuit is further operable to:

switch between the first mode and the second mode depending on a timingof receiving the feedback with respect to a reference time value in eachof the multiple cycles.

Clause C27. The apparatus as in any of one or more clauses C15-C26, C28,wherein the primary circuit is further operable to:

during a first cycle of inputting energy to the primary winding andreceiving the energy through the secondary winding:

start a timer to track passage of time; and

use the timer to determine a time corresponding to receipt of thefeedback at the primary winding.

Clause C28. The apparatus as in any of one or more clauses C15-C27,wherein the primary circuit is further operable to:

compare the time to a setpoint time value, the setpoint time valuecorresponding to a minimum desired frequency of inputting energy intothe primary winding over multiple cycles; and

to prevent operation below the minimum desired frequency, while in thefirst mode, use results of the comparison to adjust a magnitude of apulse duration of energizing the primary winding on a second cycle withrespect to a magnitude of a pulse duration of energizing the primarywinding on the first cycle.

Clause C29. Computer-readable storage media having instructions storedthereon for processing data information, such that the instructions,when carried out by computer processor hardware, cause the computerprocessor hardware to perform operations of:

operating a power converter circuit to input energy to a primary windingof a transformer and subsequently receive the energy through a secondarywinding of the transformer over multiple cycles, the power convertercircuit producing an output voltage using the energy received throughthe secondary winding; and

switching modal operation of the power converter circuit between a firstmode and a second mode over a range of different magnitudes of powerdelivered by the output voltage to a dynamic load.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of the presentapplication as defined by the appended claims. Such variations areintended to be covered by the scope of this present application. Assuch, the foregoing description of embodiments of the presentapplication is not intended to be limiting. Rather, any limitations tothe invention are presented in the following claims.

We claim:
 1. A method comprising: inputting energy to a primary windingof a transformer; receiving the energy through a secondary winding ofthe transformer; producing an output voltage from the energy receivedthrough the secondary winding; and communicating feedback through thesecondary winding to the primary winding, the communicated feedbackrepresenting state information, the state information indicating aparticular state selected amongst multiple possible states.
 2. Themethod as in claim 1, wherein inputting the energy includes controllinga flow of current through the primary winding of the transformer tostore the energy in the transformer; wherein receiving the energyincludes controlling a flow of current through the secondary winding ofthe transformer to receive the energy and produce the output voltage. 3.The method as in claim 1 further comprising: comparing a magnitude ofthe output voltage to a reference voltage; and producing the feedback tocontrol delivery of subsequent energy inputted to the primary winding tomaintain the magnitude of the output voltage within a desired voltagerange.
 4. The method as in claim 1 further comprising: controlling aflow of current through the secondary winding to communicate thefeedback from the secondary winding to the primary winding; andmonitoring a magnitude of voltage at a node of the primary winding toreceive the feedback.
 5. The method as in claim 1 further comprising:controlling a duration of energizing the secondary winding to producethe feedback.
 6. The method as in claim 5 further comprising: selectinga length of the duration from multiple durations, each of the multipledurations corresponding to a different respective state of the multiplepossible states.
 7. The method as in claim 1 further comprising:communicating the feedback though the secondary winding to the primarywinding after conveyance of the energy from the primary winding to thesecondary winding of the transformer.
 8. The method as in claim 1further comprising: monitoring a magnitude of voltage on a node of theprimary winding to receive the feedback, the magnitude of the monitoredvoltage indicating the state information associated with deriving theoutput voltage.
 9. The method as in claim 8 further comprising:controlling a magnitude of subsequent energy inputted to the primarywinding to the transformer depending on the magnitude of the monitoredvoltage indicating the state information.
 10. The method as in claim 8,wherein the magnitude of the voltage at the node of the primary windingrepresents a detected peak transition or valley transition of thevoltage at the node occurring within a monitored window of time.
 11. Themethod as in claim 1 further comprising: utilizing the feedback todetermine how to adjust an amount of subsequent energy inputted to theprimary winding to control a magnitude of the output voltage to bewithin a desired range.
 12. The method as in claim 11, utilizing thefeedback to determine an incremental amount of additional energy toinput to the primary winding on a subsequent cycle.
 13. The method as inclaim 1 further comprising: over time, repeatedly receiving feedbackcommunications inputted through the secondary winding to the primarywinding, the feedback communications indicating a different one of themultiple possible states; and repeatedly adjusting an amount ofsubsequently inputted energy to the primary winding over multiplesuccessive delivery cycles depending on the received feedbackcommunications to control a magnitude of the output voltage to be withina desired range.
 14. The method as in claim 1, wherein the multiplepossible states are selectable commands; and wherein the stateinformation is a particular command selected from the selectablecommands.
 15. The method as in claim 1 further comprising: analyzing thefeedback to obtain an error signal associated with producing the outputvoltage, the error signal indicating a difference between a magnitude ofthe output voltage and a desired setting of the output voltage; andutilizing the error signal to determine an amount of subsequent energyto input to the primary winding to control a magnitude of the outputvoltage to be within a desired range.
 16. The method as in claim 1,wherein the energy inputted to the primary winding is a first quantum ofenergy inputted to the primary winding of the transformer, the methodfurther comprising: generating the state information to representmultiple bits of data, the feedback communicated through the secondarywinding to the primary winding subsequent to receiving the first quantumof energy through the secondary winding and prior to input of a nextquantum of energy into the primary winding.
 17. An apparatus comprising:a transformer including a primary winding and a secondary winding; aprimary circuit to control input of energy to the primary winding of thetransformer; a secondary circuit to control receiving the energy throughthe secondary winding of the transformer and derive an output voltagefrom the received energy; and the secondary circuit operable tocommunicate feedback through the secondary winding to the primarywinding, the communicated feedback including state informationindicating a particular state selected amongst multiple possible states.18. The apparatus as in claim 17, wherein the primary circuit includes aprimary switch, the primary circuit controlling an ON/OFF state of theprimary switch to control a flow of current through the primary windingof the transformer to store the energy in the transformer; and whereinthe secondary circuit includes a secondary switch, the secondary circuitcontrolling an ON/OFF state of the secondary switch to control a flow ofcurrent through the secondary winding of the transformer to receive theenergy.
 19. The apparatus as in claim 17, wherein the primary circuitincludes a monitor circuit to: compare a magnitude of the output voltageto a reference voltage; and produce the feedback to control delivery ofsubsequent energy inputted to the primary winding to maintain themagnitude of the output voltage within a desired voltage range.
 20. Theapparatus as in claim 17, wherein the secondary circuit includes controlcircuitry to control a flow of current through the secondary winding tocommunicate the feedback from the secondary winding to the primarywinding; and wherein the primary circuit includes a monitor circuit tomonitor a magnitude of voltage at a node of the primary winding toreceive the feedback.
 21. The apparatus as in claim 17, wherein thesecondary circuit includes control circuitry to control a duration of aflow of current through the secondary winding to produce the stateinformation included in the feedback.
 22. The apparatus as in claim 21,wherein the secondary circuit includes control circuitry to: select alength of the duration from multiple durations, each of the multipledurations corresponding to a different respective one of the multiplepossible states.
 23. The apparatus as in claim 17, wherein the secondarycircuit utilizes a portion of the received energy to communicate thefeedback though the secondary winding to the primary winding.
 24. Theapparatus as in claim 17, wherein the primary circuit includes controlcircuitry to monitor a magnitude of voltage on a node of the primarywinding to receive the feedback, the magnitude of the monitored voltageindicating the particular state associated with deriving the outputvoltage.
 25. The apparatus as in claim 24, wherein the primary circuitincludes control circuitry to: control input of subsequent energyinputted through the primary winding to the transformer depending on themagnitude of the monitored voltage indicating the particular state. 26.The apparatus as in claim 23, wherein the magnitude of the voltage atthe node of the primary winding represents a detected peak transition orvalley transition of the voltage at the node occurring within amonitored window of time.
 27. The apparatus as in claim 17, wherein theprimary circuit includes control circuitry to utilize the feedback toadjust an amount of subsequent energy inputted to the primary winding tocontrol a magnitude of the output voltage to be within a desired range.28. The apparatus as in claim 27, wherein the control circuit isoperable to utilize the feedback to determine an incremental amount ofadditional energy to input to the primary winding on a subsequent cycle.29. The apparatus as in claim 17, wherein the primary circuit includescontrol circuitry to: over time, repeatedly receive feedbackcommunications inputted through the secondary winding, the feedbackcommunications indicating a different one of the multiple possiblestates; and repeatedly adjust an amount of subsequently inputted energyto the primary winding over multiple successive delivery cyclesdepending on the received feedback communications to control a magnitudeof the output voltage to be within a desired range.
 30. The apparatus asin claim 17, wherein the multiple possible states are selectablecommands; and wherein the particular state captured by the feedback is aparticular command selected from the multiple selectable commands. 31.The apparatus as in claim 17, wherein the secondary circuit is furtheroperable to: analyze the feedback to obtain an error signal associatedwith producing the output voltage; and utilize the error signal todetermine an amount of subsequent energy to input to the primary windingto control a magnitude of the output voltage to be within a desiredrange.
 32. The apparatus as in claim 17, wherein the energy inputted tothe primary winding is a first quantum of energy inputted to the primarywinding of the transformer; and wherein the state information in thefeedback is encoded to represent multiple bits of data, the feedbackcommunicated through the secondary winding to the primary windingsubsequent to receiving the first quantum of energy through thesecondary winding and prior to input of a next quantum of energy intothe primary winding.
 33. The apparatus as in claim 17, wherein theprimary circuit is powered with respect to a first ground referencevoltage; and wherein the secondary circuit is powered with respect to asecond ground reference voltage, the primary circuit electricallyisolated from the secondary circuit via the transformer. 34.Computer-readable storage media having instructions stored thereon forprocessing data information, such that the instructions, when carriedout by computer processor hardware, cause the computer processorhardware to perform operations of: controlling input of energy to aprimary winding of a transformer; controlling receipt of the energythrough a secondary winding of the transformer to produce an outputvoltage; and communicating feedback through the secondary winding to theprimary winding, the communicated feedback representing stateinformation, the state information indicating a particular state amongstmultiple possible states.
 35. The method as in claim 1, whereincommunicating the feedback through the secondary winding to the primarywinding includes: comparing a voltage level of a node of the secondarywinding to a threshold value; and controlling timing of conveying thefeedback through the secondary winding to the primary winding to occurwhen the voltage level of the node of the secondary winding is below thethreshold value.
 36. The method as in claim 1, wherein communicating thefeedback through the secondary winding to the primary winding includes:delaying timing of conveying the feedback through the secondary windingto the primary winding until a time of detecting that the magnitude of amonitored voltage is below a threshold value.
 37. The apparatus as inclaim 17, wherein the primary circuit is operable to control a rate ofinputting energy into the primary winding to be below a threshold valueto limit an amount of current that the output voltage supplies to arespective load.